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Correcting some usage of Bold and Italics (files). Adding some missing SEE ALSO. Fixing missed replaceable paths that are configurable. Be careful about .P in .TP sections - need to use .sp for space line. Use .UR/.UE for URL references.
1306 lines
38 KiB
Plaintext
1306 lines
38 KiB
Plaintext
.TH "LVMTHIN" "7" "LVM TOOLS #VERSION#" "Red Hat, Inc" "\""
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.
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.SH NAME
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.
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lvmthin \(em LVM thin provisioning
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.
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.SH DESCRIPTION
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.
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Blocks in a standard \fBlvm\fP(8) Logical Volume (LV) are allocated when
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the LV is created, but blocks in a thin provisioned LV are allocated as
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they are written. Because of this, a thin provisioned LV is given a
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virtual size, and can then be much larger than physically available
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storage. The amount of physical storage provided for thin provisioned LVs
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can be increased later as the need arises.
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.P
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Blocks in a standard LV are allocated (during creation) from the Volume
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Group (VG), but blocks in a thin LV are allocated (during use) from a
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special "thin pool LV". The thin pool LV contains blocks of physical
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storage, and blocks in thin LVs just reference blocks in the thin pool LV.
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.P
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A thin pool LV must be created before thin LVs can be created within it.
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A thin pool LV is created by combining two standard LVs: a large data LV
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that will hold blocks for thin LVs, and a metadata LV that will hold
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metadata. The metadata tracks which data blocks belong to each thin LV.
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.P
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Snapshots of thin LVs are efficient because the data blocks common to a
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thin LV and any of its snapshots are shared. Snapshots may be taken of
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thin LVs or of other thin snapshots. Blocks common to recursive snapshots
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are also shared in the thin pool. There is no limit to or degradation
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from sequences of snapshots.
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.P
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As thin LVs or snapshot LVs are written to, they consume data blocks in
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the thin pool. As free data blocks in the pool decrease, more free blocks
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may need to be supplied. This is done by extending the thin pool data LV
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with additional physical space from the VG. Removing thin LVs or
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snapshots from the thin pool can also free blocks in the thin pool.
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However, removing LVs is not always an effective way of freeing space in a
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thin pool because the amount is limited to the number of blocks not shared
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with other LVs in the pool.
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.P
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Incremental block allocation from thin pools can cause thin LVs to become
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fragmented. Standard LVs generally avoid this problem by allocating all
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the blocks at once during creation.
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.
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.SH THIN TERMS
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.
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.TP
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ThinDataLV
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.br
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thin data LV
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.br
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large LV created in a VG
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.br
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used by thin pool to store ThinLV blocks
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.
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.TP
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ThinMetaLV
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.br
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thin metadata LV
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.br
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small LV created in a VG
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.br
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used by thin pool to track data block usage
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.
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.TP
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ThinPoolLV
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.br
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thin pool LV
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.br
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combination of ThinDataLV and ThinMetaLV
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.br
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contains ThinLVs and SnapLVs
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.
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.TP
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ThinLV
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.br
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thin LV
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.br
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created from ThinPoolLV
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.br
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appears blank after creation
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.
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.TP
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SnapLV
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.br
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snapshot LV
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.br
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created from ThinPoolLV
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.br
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appears as a snapshot of another LV after creation
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.
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.SH THIN USAGE
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.
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The primary method for using lvm thin provisioning:
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.nr step 1 1
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.
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.SS \n[step]. Create ThinDataLV
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.
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Create an LV that will hold thin pool data.
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.P
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.B lvcreate -n ThinDataLV -L LargeSize VG
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.P
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.I Example
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.br
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# lvcreate -n pool0 -L 10G vg
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.
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.SS \n+[step]. Create ThinMetaLV
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.
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Create an LV that will hold thin pool metadata.
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.P
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.B lvcreate -n ThinMetaLV -L SmallSize VG
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.P
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.I Example
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.br
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# lvcreate -n pool0meta -L 1G vg
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.P
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# lvs
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LV VG Attr LSize
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pool0 vg -wi-a----- 10.00g
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pool0meta vg -wi-a----- 1.00g
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.
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.SS \n+[step]. Create ThinPoolLV
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.
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.nf
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Combine the data and metadata LVs into a thin pool LV.
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ThinDataLV is renamed to hidden ThinPoolLV_tdata.
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ThinMetaLV is renamed to hidden ThinPoolLV_tmeta.
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The new ThinPoolLV takes the previous name of ThinDataLV.
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.fi
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.P
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.B lvconvert --type thin-pool --poolmetadata VG/ThinMetaLV VG/ThinDataLV
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.P
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.I Example
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.br
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# lvconvert --type thin-pool --poolmetadata vg/pool0meta vg/pool0
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.P
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# lvs vg/pool0
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LV VG Attr LSize Pool Origin Data% Meta%
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pool0 vg twi-a-tz-- 10.00g 0.00 0.00
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.P
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# lvs -a
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LV VG Attr LSize
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pool0 vg twi-a-tz-- 10.00g
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[pool0_tdata] vg Twi-ao---- 10.00g
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[pool0_tmeta] vg ewi-ao---- 1.00g
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.
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.SS \n+[step]. Create ThinLV
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.
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.nf
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Create a new thin LV from the thin pool LV.
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The thin LV is created with a virtual size.
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Multiple new thin LVs may be created in the thin pool.
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Thin LV names must be unique in the VG.
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The '--type thin' option is inferred from the virtual size option.
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The --thinpool argument specifies which thin pool will
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contain the ThinLV.
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.fi
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.P
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.B lvcreate -n ThinLV -V VirtualSize --thinpool ThinPoolLV VG
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.P
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.I Example
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.br
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Create a thin LV in a thin pool:
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.br
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# lvcreate -n thin1 -V 1T --thinpool pool0 vg
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.P
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Create another thin LV in the same thin pool:
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.br
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# lvcreate -n thin2 -V 1T --thinpool pool0 vg
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.P
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# lvs vg/thin1 vg/thin2
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LV VG Attr LSize Pool Origin Data%
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thin1 vg Vwi-a-tz-- 1.00t pool0 0.00
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thin2 vg Vwi-a-tz-- 1.00t pool0 0.00
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.
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.SS \n+[step]. Create SnapLV
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.
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Create snapshots of an existing ThinLV or SnapLV.
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.br
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Do not specify
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.BR -L ", " --size
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when creating a thin snapshot.
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.br
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A size argument will cause an old COW snapshot to be created.
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.P
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.B lvcreate -n SnapLV --snapshot VG/ThinLV
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.br
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.B lvcreate -n SnapLV --snapshot VG/PrevSnapLV
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.P
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.I Example
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.br
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Create first snapshot of an existing ThinLV:
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.br
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# lvcreate -n thin1s1 -s vg/thin1
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.P
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Create second snapshot of the same ThinLV:
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.br
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# lvcreate -n thin1s2 -s vg/thin1
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.P
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Create a snapshot of the first snapshot:
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.br
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# lvcreate -n thin1s1s1 -s vg/thin1s1
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.P
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# lvs vg/thin1s1 vg/thin1s2 vg/thin1s1s1
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LV VG Attr LSize Pool Origin
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thin1s1 vg Vwi---tz-k 1.00t pool0 thin1
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thin1s2 vg Vwi---tz-k 1.00t pool0 thin1
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thin1s1s1 vg Vwi---tz-k 1.00t pool0 thin1s1
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.
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.SS \n+[step]. Activate SnapLV
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.
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Thin snapshots are created with the persistent "activation skip"
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flag, indicated by the "k" attribute. Use -K with lvchange
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or vgchange to activate thin snapshots with the "k" attribute.
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.P
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.B lvchange -ay -K VG/SnapLV
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.P
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.I Example
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.br
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# lvchange -ay -K vg/thin1s1
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.P
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# lvs vg/thin1s1
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LV VG Attr LSize Pool Origin
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thin1s1 vg Vwi-a-tz-k 1.00t pool0 thin1
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.
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.SH THIN TOPICS
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.
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.B Automatic pool metadata LV
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.br
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.B Specify devices for data and metadata LVs
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.br
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.B Tolerate device failures using raid
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.br
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.B Spare metadata LV
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.br
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.B Metadata check and repair
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.br
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.B Activation of thin snapshots
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.br
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.B Removing thin pool LVs, thin LVs and snapshots
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.br
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.B Manually manage free data space of thin pool LV
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.br
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.B Manually manage free metadata space of a thin pool LV
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.br
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.B Using fstrim to increase free space in a thin pool LV
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.br
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.B Automatically extend thin pool LV
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.br
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.B Data space exhaustion
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.br
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.B Metadata space exhaustion
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.br
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.B Automatic extend settings
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.br
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.B Zeroing
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.br
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.B Discard
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.br
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.B Chunk size
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.br
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.B Size of pool metadata LV
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.br
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.B Create a thin snapshot of an external, read only LV
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.br
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.B Convert a standard LV to a thin LV with an external origin
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.br
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.B Single step thin pool LV creation
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.br
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.B Single step thin pool LV and thin LV creation
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.br
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.B Merge thin snapshots
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.br
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.B XFS on snapshots
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.
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.SS Automatic pool metadata LV
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.
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A thin data LV can be converted to a thin pool LV without specifying a
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thin pool metadata LV. LVM automatically creates a metadata LV from the
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same VG.
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.P
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.B lvcreate -n ThinDataLV -L LargeSize VG
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.br
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.B lvconvert --type thin-pool VG/ThinDataLV
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.P
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.I Example
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.br
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.nf
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# lvcreate -n pool0 -L 10G vg
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# lvconvert --type thin-pool vg/pool0
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.P
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# lvs -a
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pool0 vg twi-a-tz-- 10.00g
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[pool0_tdata] vg Twi-ao---- 10.00g
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[pool0_tmeta] vg ewi-ao---- 16.00m
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.fi
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.
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.SS Specify devices for data and metadata LVs
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.
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The data and metadata LVs in a thin pool are best created on
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separate physical devices. To do that, specify the device name(s)
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at the end of the lvcreate line. It can be especially helpful
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to use fast devices for the metadata LV.
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.P
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.B lvcreate -n ThinDataLV -L LargeSize VG LargePV
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.br
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.B lvcreate -n ThinMetaLV -L SmallSize VG SmallPV
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.br
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.B lvconvert --type thin-pool --poolmetadata VG/ThinMetaLV VG/ThinDataLV
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.P
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.I Example
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.nf
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# lvcreate -n pool0 -L 10G vg /dev/sdA
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# lvcreate -n pool0meta -L 1G vg /dev/sdB
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# lvconvert --type thin-pool --poolmetadata vg/pool0meta vg/pool0
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.fi
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.P
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.BR lvm.conf (5)
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.B thin_pool_metadata_require_separate_pvs
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.br
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controls the default PV usage for thin pool creation.
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.
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.SS Tolerate device failures using raid
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.
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To tolerate device failures, use raid for the pool data LV and
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pool metadata LV. This is especially recommended for pool metadata LVs.
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.P
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.B lvcreate --type raid1 -m 1 -n ThinMetaLV -L SmallSize VG PVA PVB
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.br
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.B lvcreate --type raid1 -m 1 -n ThinDataLV -L LargeSize VG PVC PVD
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.br
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.B lvconvert --type thin-pool --poolmetadata VG/ThinMetaLV VG/ThinDataLV
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.P
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.I Example
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.nf
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# lvcreate --type raid1 -m 1 -n pool0 -L 10G vg /dev/sdA /dev/sdB
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# lvcreate --type raid1 -m 1 -n pool0meta -L 1G vg /dev/sdC /dev/sdD
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# lvconvert --type thin-pool --poolmetadata vg/pool0meta vg/pool0
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.fi
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.
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.SS Spare metadata LV
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.
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The first time a thin pool LV is created, lvm will create a spare
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metadata LV in the VG. This behavior can be controlled with the
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option --poolmetadataspare y|n. (Future thin pool creations will
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also attempt to create the pmspare LV if none exists.)
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.P
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To create the pmspare ("pool metadata spare") LV, lvm first creates
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an LV with a default name, e.g. lvol0, and then converts this LV to
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a hidden LV with the _pmspare suffix, e.g. lvol0_pmspare.
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.P
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One pmspare LV is kept in a VG to be used for any thin pool.
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.P
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The pmspare LV cannot be created explicitly, but may be removed
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explicitly.
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.P
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.I Example
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.nf
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# lvcreate -n pool0 -L 10G vg
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# lvcreate -n pool0meta -L 1G vg
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# lvconvert --type thin-pool --poolmetadata vg/pool0meta vg/pool0
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.P
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# lvs -a
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[lvol0_pmspare] vg ewi-------
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pool0 vg twi---tz--
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[pool0_tdata] vg Twi-------
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[pool0_tmeta] vg ewi-------
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.fi
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.P
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The "Metadata check and repair" section describes the use of
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the pmspare LV.
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.
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.SS Metadata check and repair
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.
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If thin pool metadata is damaged, it may be repairable.
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Checking and repairing thin pool metadata is analogous to
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running fsck/repair on a file system.
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.P
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When a thin pool LV is activated, lvm runs the thin_check command
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to check the correctness of the metadata on the pool metadata LV.
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.P
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.BR lvm.conf (5)
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.B thin_check_executable
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.br
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can be set to an empty string ("") to disable the thin_check step.
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This is not recommended.
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.P
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.BR lvm.conf (5)
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.B thin_check_options
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.br
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controls the command options used for the thin_check command.
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.P
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If the thin_check command finds a problem with the metadata,
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the thin pool LV is not activated, and the thin pool metadata needs
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to be repaired.
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.P
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Simple repair commands are not always successful. Advanced repair may
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require editing thin pool metadata and lvm metadata. Newer versions of
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the kernel and lvm tools may be more successful at repair. Report the
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details of damaged thin metadata to get the best advice on recovery.
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.P
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Command to repair a thin pool:
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.br
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.B lvconvert --repair VG/ThinPoolLV
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.P
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Repair performs the following steps:
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.P
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.nr step 1 1
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.IP \n[step] 3
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Creates a new, repaired copy of the metadata.
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.br
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lvconvert runs the thin_repair command to read damaged metadata
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from the existing pool metadata LV, and writes a new repaired
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copy to the VG's pmspare LV.
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.IP \n+[step] 3
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Replaces the thin pool metadata LV.
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.br
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If step 1 is successful, the thin pool metadata LV is replaced
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with the pmspare LV containing the corrected metadata.
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The previous thin pool metadata LV, containing the damaged metadata,
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becomes visible with the new name ThinPoolLV_metaN (where N is 0,1,...).
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.P
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If the repair works, the thin pool LV and its thin LVs can be activated.
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User should manually check if repaired thin pool kernel metadata
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has all data for all lvm2 known LVs by individual activation of
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every thin LV. When all works, user should continue with fsck of
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all filesystems present on these volumes.
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Once the thin pool is considered fully functional user may remove ThinPoolLV_metaN
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(the LV containing the damaged thin pool metadata) for possible
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space reuse.
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For a better performance it may be useful to pvmove the new repaired metadata LV
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(written to previous pmspare volume) to a faster PV, e.g. SSD.
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.P
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If the repair operation fails, the thin pool LV and its thin LVs
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are not accessible and it may be necessary to restore their content
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from a backup. In such case the content of unmodified original damaged
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ThinPoolLV_metaN volume can be used by your support for more
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advanced recovery methods.
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.P
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If metadata is manually restored with thin_repair directly,
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the pool metadata LV can be manually swapped with another LV
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containing new metadata:
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.P
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.B lvconvert --thinpool VG/ThinPoolLV --poolmetadata VG/NewThinMetaLV
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.P
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Note: Thin pool metadata is compact so even small corruptions
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in them may result in significant portions of mappings to be lost.
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It is recommended to use fast resilient storage for them.
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.
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.SS Activation of thin snapshots
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.
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When a thin snapshot LV is created, it is by default given the
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"activation skip" flag. This flag is indicated by the "k" attribute
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displayed by lvs:
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.P
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.nf
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# lvs vg/thin1s1
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LV VG Attr LSize Pool Origin
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thin1s1 vg Vwi---tz-k 1.00t pool0 thin1
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.fi
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.P
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This flag causes the snapshot LV to be skipped, i.e. not activated,
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by normal activation commands. The skipping behavior does not
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apply to deactivation commands.
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.P
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A snapshot LV with the "k" attribute can be activated using
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the -K (or --ignoreactivationskip) option in addition to the
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standard -ay (or --activate y) option.
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.P
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Command to activate a thin snapshot LV:
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.br
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.B lvchange -ay -K VG/SnapLV
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.P
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The persistent "activation skip" flag can be turned off during
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lvcreate, or later with lvchange using the -kn
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(or --setactivationskip n) option.
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It can be turned on again with -ky (or --setactivationskip y).
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.P
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When the "activation skip" flag is removed, normal activation
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commands will activate the LV, and the -K activation option is
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not needed.
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.P
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Command to create snapshot LV without the activation skip flag:
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.br
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.B lvcreate -kn -n SnapLV -s VG/ThinLV
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.P
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Command to remove the activation skip flag from a snapshot LV:
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.br
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.B lvchange -kn VG/SnapLV
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.P
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.BR lvm.conf (5)
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.B auto_set_activation_skip
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.br
|
|
controls the default activation skip setting used by lvcreate.
|
|
.
|
|
.SS Removing thin pool LVs, thin LVs and snapshots
|
|
.
|
|
Removing a thin LV and its related snapshots returns the blocks it
|
|
used to the thin pool LV. These blocks will be reused for other
|
|
thin LVs and snapshots.
|
|
.P
|
|
Removing a thin pool LV removes both the data LV and metadata LV
|
|
and returns the space to the VG.
|
|
.P
|
|
lvremove of thin pool LVs, thin LVs and snapshots cannot be
|
|
reversed with vgcfgrestore.
|
|
.P
|
|
vgcfgbackup does not back up thin pool metadata.
|
|
.
|
|
.SS Manually manage free data space of thin pool LV
|
|
.
|
|
The available free space in a thin pool LV can be displayed
|
|
with the lvs command. Free space can be added by extending
|
|
the thin pool LV.
|
|
.P
|
|
Command to extend thin pool data space:
|
|
.br
|
|
.B lvextend -L Size VG/ThinPoolLV
|
|
.P
|
|
.I Example
|
|
.br
|
|
.nf
|
|
1. A thin pool LV is using 26.96% of its data blocks.
|
|
# lvs
|
|
LV VG Attr LSize Pool Origin Data%
|
|
pool0 vg twi-a-tz-- 10.00g 26.96
|
|
.P
|
|
2. Double the amount of physical space in the thin pool LV.
|
|
# lvextend -L+10G vg/pool0
|
|
.P
|
|
3. The percentage of used data blocks is half the previous value.
|
|
# lvs
|
|
LV VG Attr LSize Pool Origin Data%
|
|
pool0 vg twi-a-tz-- 20.00g 13.48
|
|
.fi
|
|
.P
|
|
Other methods of increasing free data space in a thin pool LV
|
|
include removing a thin LV and its related snapshots, or running
|
|
fstrim on the file system using a thin LV.
|
|
.
|
|
.SS Manually manage free metadata space of a thin pool LV
|
|
.
|
|
The available metadata space in a thin pool LV can be displayed
|
|
with the lvs -o+metadata_percent command.
|
|
.P
|
|
Command to extend thin pool metadata space:
|
|
.br
|
|
.B lvextend --poolmetadatasize Size VG/ThinPoolLV
|
|
.P
|
|
.I Example
|
|
.br
|
|
1. A thin pool LV is using 12.40% of its metadata blocks.
|
|
.nf
|
|
# lvs -oname,size,data_percent,metadata_percent vg/pool0
|
|
LV LSize Data% Meta%
|
|
pool0 20.00g 13.48 12.40
|
|
.fi
|
|
.P
|
|
2. Display a thin pool LV with its component thin data LV and thin metadata LV.
|
|
.nf
|
|
# lvs -a -oname,attr,size vg
|
|
LV Attr LSize
|
|
pool0 twi-a-tz-- 20.00g
|
|
[pool0_tdata] Twi-ao---- 20.00g
|
|
[pool0_tmeta] ewi-ao---- 12.00m
|
|
.fi
|
|
.P
|
|
3. Double the amount of physical space in the thin metadata LV.
|
|
.nf
|
|
# lvextend --poolmetadatasize +12M vg/pool0
|
|
.fi
|
|
.P
|
|
4. The percentage of used metadata blocks is half the previous value.
|
|
.nf
|
|
# lvs -a -oname,size,data_percent,metadata_percent vg
|
|
LV LSize Data% Meta%
|
|
pool0 20.00g 13.48 6.20
|
|
[pool0_tdata] 20.00g
|
|
[pool0_tmeta] 24.00m
|
|
.fi
|
|
.
|
|
.SS Using fstrim to increase free space in a thin pool LV
|
|
.
|
|
Removing files in a file system on top of a thin LV does not
|
|
generally add free space back to the thin pool. Manually running
|
|
the fstrim command can return space back to the thin pool that had
|
|
been used by removed files. fstrim uses discards and will not work
|
|
if the thin pool LV has discards mode set to ignore.
|
|
.P
|
|
.I Example
|
|
.br
|
|
A thin pool has 10G of physical data space, and a thin LV has a virtual
|
|
size of 100G. Writing a 1G file to the file system reduces the
|
|
free space in the thin pool by 10% and increases the virtual usage
|
|
of the file system by 1%. Removing the 1G file restores the virtual
|
|
1% to the file system, but does not restore the physical 10% to the
|
|
thin pool. The fstrim command restores the physical space to the thin pool.
|
|
.P
|
|
.nf
|
|
# lvs -a -oname,attr,size,pool_lv,origin,data_percent,metadata_percent vg
|
|
LV Attr LSize Pool Origin Data% Meta%
|
|
pool0 twi-a-tz-- 10.00g 47.01 21.03
|
|
thin1 Vwi-aotz-- 100.00g pool0 2.70
|
|
.P
|
|
# df -h /mnt/X
|
|
Filesystem Size Used Avail Use% Mounted on
|
|
/dev/mapper/vg-thin1 99G 1.1G 93G 2% /mnt/X
|
|
.P
|
|
# dd if=/dev/zero of=/mnt/X/1Gfile bs=4096 count=262144; sync
|
|
.P
|
|
# lvs
|
|
pool0 vg twi-a-tz-- 10.00g 57.01 25.26
|
|
thin1 vg Vwi-aotz-- 100.00g pool0 3.70
|
|
.P
|
|
# df -h /mnt/X
|
|
/dev/mapper/vg-thin1 99G 2.1G 92G 3% /mnt/X
|
|
.P
|
|
# rm /mnt/X/1Gfile
|
|
.P
|
|
# lvs
|
|
pool0 vg twi-a-tz-- 10.00g 57.01 25.26
|
|
thin1 vg Vwi-aotz-- 100.00g pool0 3.70
|
|
.P
|
|
# df -h /mnt/X
|
|
/dev/mapper/vg-thin1 99G 1.1G 93G 2% /mnt/X
|
|
.P
|
|
# fstrim -v /mnt/X
|
|
.P
|
|
# lvs
|
|
pool0 vg twi-a-tz-- 10.00g 47.01 21.03
|
|
thin1 vg Vwi-aotz-- 100.00g pool0 2.70
|
|
.fi
|
|
.P
|
|
The "Discard" section covers an option for automatically freeing data
|
|
space in a thin pool.
|
|
.
|
|
.SS Automatically extend thin pool LV
|
|
.
|
|
The lvm daemon dmeventd (lvm2-monitor) monitors the data usage of thin
|
|
pool LVs and extends them when the usage reaches a certain level. The
|
|
necessary free space must exist in the VG to extend thin pool LVs.
|
|
Monitoring and extension of thin pool LVs are controlled independently.
|
|
.P
|
|
\(em Monitoring \(em
|
|
.P
|
|
When a thin pool LV is activated, dmeventd will begin monitoring it by
|
|
default.
|
|
.sp
|
|
Command to start or stop dmeventd monitoring a thin pool LV:
|
|
.br
|
|
.B lvchange --monitor y|n VG/ThinPoolLV
|
|
.sp
|
|
The current dmeventd monitoring status of a thin pool LV can be displayed
|
|
with the command lvs -o+seg_monitor.
|
|
.P
|
|
\(em Autoextending \(em
|
|
.P
|
|
dmeventd should be configured to extend thin pool LVs before all data
|
|
space is used. Warnings are emitted through syslog when the use of a thin
|
|
pool reaches 80%, 85%, 90% and 95%. (See the section "Data space
|
|
exhaustion" for the effects of not extending a thin pool LV.) The point
|
|
at which dmeventd extends thin pool LVs, and the amount are controlled
|
|
with two configuration settings:
|
|
.P
|
|
.BR lvm.conf (5)
|
|
.B thin_pool_autoextend_threshold
|
|
.br
|
|
is a percentage full value that defines when the thin pool LV should be
|
|
extended. Setting this to 100 disables automatic extension. The minimum
|
|
value is 50.
|
|
.P
|
|
.BR lvm.conf (5)
|
|
.B thin_pool_autoextend_percent
|
|
.br
|
|
defines how much extra data space should be added to the thin pool LV from
|
|
the VG, in percent of its current size.
|
|
.P
|
|
\(em Disabling \(em
|
|
.P
|
|
There are multiple ways that extension of thin pools could be prevented:
|
|
.IP \[bu] 2
|
|
If the dmeventd daemon is not running, no monitoring or automatic
|
|
extension will occur.
|
|
.
|
|
.IP \[bu]
|
|
Even when dmeventd is running, all monitoring can be disabled with the
|
|
lvm.conf monitoring setting.
|
|
.
|
|
.IP \[bu]
|
|
To activate or create a thin pool LV without interacting with dmeventd,
|
|
the --ignoremonitoring option can be used. With this option, the command
|
|
will not ask dmeventd to monitor the thin pool LV.
|
|
.
|
|
.IP \[bu]
|
|
Setting thin_pool_autoextend_threshold to 100 disables automatic
|
|
extension of thin pool LVs, even if they are being monitored by dmeventd.
|
|
.P
|
|
.I Example
|
|
.br
|
|
If thin_pool_autoextend_threshold is 70 and thin_pool_autoextend_percent is 20,
|
|
whenever a pool exceeds 70% usage, it will be extended by another 20%.
|
|
For a 1G pool, using 700M will trigger a resize to 1.2G. When the usage exceeds
|
|
840M, the pool will be extended to 1.44G, and so on.
|
|
.
|
|
.SS Data space exhaustion
|
|
.
|
|
When properly managed, thin pool data space should be extended before it
|
|
is all used (see the section "Automatically extend thin pool LV"). If
|
|
thin pool data space is already exhausted, it can still be extended (see
|
|
the section "Manually manage free data space of thin pool LV".)
|
|
.P
|
|
The behavior of a full thin pool is configurable with the --errorwhenfull
|
|
y|n option to lvcreate or lvchange. The errorwhenfull setting applies
|
|
only to writes; reading thin LVs can continue even when data space is
|
|
exhausted.
|
|
.P
|
|
Command to change the handling of a full thin pool:
|
|
.br
|
|
.B lvchange --errorwhenfull y|n VG/ThinPoolLV
|
|
.P
|
|
.BR lvm.conf (5)
|
|
.B error_when_full
|
|
.br
|
|
controls the default error when full behavior.
|
|
.P
|
|
The current setting of a thin pool LV can be displayed with the command:
|
|
lvs -o+lv_when_full.
|
|
.P
|
|
The errorwhenfull setting does not effect the monitoring and autoextend
|
|
settings, and the monitoring/autoextend settings do not effect the
|
|
errorwhenfull setting. It is only when monitoring/autoextend are not
|
|
effective that the thin pool becomes full and the errorwhenfull setting is
|
|
applied.
|
|
.P
|
|
\(em errorwhenfull n \(em
|
|
.P
|
|
This is the default. Writes to thin LVs are accepted and queued, with the
|
|
expectation that pool data space will be extended soon. Once data space
|
|
is extended, the queued writes will be processed, and the thin pool will
|
|
return to normal operation.
|
|
.P
|
|
While waiting to be extended, the thin pool will queue writes for up to 60
|
|
seconds (the default). If data space has not been extended after this
|
|
time, the queued writes will return an error to the caller, e.g. the file
|
|
system. This can result in file system corruption for non-journaled file
|
|
systems that may require repair. When a thin pool returns errors for writes
|
|
to a thin LV, any file system is subject to losing unsynced user data.
|
|
.P
|
|
The 60 second timeout can be changed or disabled with the dm-thin-pool
|
|
kernel module option
|
|
.B no_space_timeout.
|
|
This option sets the number of seconds that thin pools will queue writes.
|
|
If set to 0, writes will not time out. Disabling timeouts can result in
|
|
the system running out of resources, memory exhaustion, hung tasks, and
|
|
deadlocks. (The timeout applies to all thin pools on the system.)
|
|
.P
|
|
\(em errorwhenfull y \(em
|
|
.P
|
|
Writes to thin LVs immediately return an error, and no writes are queued.
|
|
In the case of a file system, this can result in corruption that may
|
|
require fs repair (the specific consequences depend on the thin LV user.)
|
|
.P
|
|
\(em data percent \(em
|
|
.P
|
|
When data space is exhausted, the lvs command displays 100 under Data% for
|
|
the thin pool LV:
|
|
.P
|
|
.nf
|
|
# lvs vg/pool0
|
|
LV VG Attr LSize Pool Origin Data%
|
|
pool0 vg twi-a-tz-- 512.00m 100.00
|
|
.fi
|
|
.P
|
|
\(em causes \(em
|
|
.P
|
|
A thin pool may run out of data space for any of the following reasons:
|
|
.
|
|
.IP \[bu] 2
|
|
Automatic extension of the thin pool is disabled, and the thin pool is not
|
|
manually extended. (Disabling automatic extension is not recommended.)
|
|
.
|
|
.IP \[bu]
|
|
The dmeventd daemon is not running and the thin pool is not manually
|
|
extended. (Disabling dmeventd is not recommended.)
|
|
.
|
|
.IP \[bu]
|
|
Automatic extension of the thin pool is too slow given the rate of writes
|
|
to thin LVs in the pool. (This can be addressed by tuning the
|
|
thin_pool_autoextend_threshold and thin_pool_autoextend_percent.
|
|
See "Automatic extend settings".)
|
|
.
|
|
.IP \[bu]
|
|
The VG does not have enough free blocks to extend the thin pool.
|
|
.
|
|
.SS Metadata space exhaustion
|
|
.
|
|
If thin pool metadata space is exhausted (or a thin pool metadata
|
|
operation fails), errors will be returned for IO operations on thin LVs.
|
|
.P
|
|
When metadata space is exhausted, the lvs command displays 100 under Meta%
|
|
for the thin pool LV:
|
|
.P
|
|
.nf
|
|
# lvs -o lv_name,size,data_percent,metadata_percent vg/pool0
|
|
LV LSize Data% Meta%
|
|
pool0 100.00
|
|
.fi
|
|
.P
|
|
The same reasons for thin pool data space exhaustion apply to thin pool
|
|
metadata space.
|
|
.P
|
|
Metadata space exhaustion can lead to inconsistent thin pool metadata and
|
|
inconsistent file systems, so the response requires offline checking and
|
|
repair.
|
|
.TP 4
|
|
1.
|
|
Deactivate the thin pool LV, or reboot the system if this is not possible.
|
|
.TP
|
|
2.
|
|
Repair thin pool with lvconvert --repair.
|
|
.br
|
|
See "Metadata check and repair".
|
|
.TP
|
|
3.
|
|
Extend pool metadata space with lvextend --poolmetadatasize.
|
|
.br
|
|
See "Manually manage free metadata space of a thin pool LV".
|
|
.TP
|
|
4.
|
|
Check and repair file system.
|
|
.
|
|
.SS Automatic extend settings
|
|
.
|
|
Thin pool LVs can be extended according to preset values. The presets
|
|
determine if the LV should be extended based on how full it is, and if so
|
|
by how much. When dmeventd monitors thin pool LVs, it uses lvextend with
|
|
these presets. (See "Automatically extend thin pool LV".)
|
|
.P
|
|
Command to extend a thin pool data LV using presets:
|
|
.br
|
|
.B lvextend --use-policies VG/ThinPoolLV
|
|
.P
|
|
The command uses these settings:
|
|
.P
|
|
.BR lvm.conf (5)
|
|
.B thin_pool_autoextend_threshold
|
|
.br
|
|
autoextend the LV when its usage exceeds this percent.
|
|
.P
|
|
.BR lvm.conf (5)
|
|
.B thin_pool_autoextend_percent
|
|
.br
|
|
autoextend the LV by this much additional space.
|
|
.P
|
|
To see the default values of these settings, run:
|
|
.P
|
|
.B lvmconfig --type default --withcomment
|
|
.RS
|
|
.B activation/thin_pool_autoextend_threshold
|
|
.RE
|
|
.P
|
|
.B lvmconfig --type default --withcomment
|
|
.RS
|
|
.B activation/thin_pool_autoextend_percent
|
|
.RE
|
|
.P
|
|
To change these values globally, edit
|
|
.BR lvm.conf (5).
|
|
.P
|
|
To change these values on a per-VG or per-LV basis, attach a "profile" to
|
|
the VG or LV. A profile is a collection of config settings, saved in a
|
|
local text file (using the lvm.conf format). lvm looks for profiles in
|
|
the profile_dir directory, e.g. \fI#DEFAULT_SYS_DIR#/profile/\fP. Once attached to a VG
|
|
or LV, lvm will process the VG or LV using the settings from the attached
|
|
profile. A profile is named and referenced by its file name.
|
|
.P
|
|
To use a profile to customize the lvextend settings for an LV:
|
|
.
|
|
.IP \[bu] 2
|
|
Create a file containing settings, saved in profile_dir.
|
|
.br
|
|
For the profile_dir location, run:
|
|
.br
|
|
.B lvmconfig config/profile_dir
|
|
.
|
|
.IP \[bu]
|
|
Attach the profile to an LV, using the command:
|
|
.br
|
|
.B lvchange --metadataprofile ProfileName VG/ThinPoolLV
|
|
.
|
|
.IP \[bu]
|
|
Extend the LV using the profile settings:
|
|
.br
|
|
.B lvextend --use-policies VG/ThinPoolLV
|
|
.P
|
|
.I Example
|
|
.br
|
|
.nf
|
|
# lvmconfig config/profile_dir
|
|
profile_dir="#DEFAULT_SYS_DIR#/profile"
|
|
.P
|
|
# cat #DEFAULT_SYS_DIR#/profile/pool0extend.profile
|
|
activation {
|
|
.RS
|
|
thin_pool_autoextend_threshold=50
|
|
thin_pool_autoextend_percent=10
|
|
.RE
|
|
}
|
|
.P
|
|
# lvchange --metadataprofile pool0extend vg/pool0
|
|
.P
|
|
# lvextend --use-policies vg/pool0
|
|
.fi
|
|
.P
|
|
Notes
|
|
.
|
|
.IP \[bu] 2
|
|
A profile is attached to a VG or LV by name, where the name references a
|
|
local file in profile_dir. If the VG is moved to another machine, the
|
|
file with the profile also needs to be moved.
|
|
.
|
|
.IP \[bu]
|
|
Only certain settings can be used in a VG or LV profile, see:
|
|
.br
|
|
.B lvmconfig --type profilable-metadata.
|
|
.
|
|
.IP \[bu]
|
|
An LV without a profile of its own will inherit the VG profile.
|
|
.
|
|
.IP \[bu]
|
|
Remove a profile from an LV using the command:
|
|
.br
|
|
.B lvchange --detachprofile VG/ThinPoolLV.
|
|
.
|
|
.IP \[bu]
|
|
Commands can also have profiles applied to them. The settings that can be
|
|
applied to a command are different than the settings that can be applied
|
|
to a VG or LV. See lvmconfig --type profilable-command. To apply a
|
|
profile to a command, write a profile, save it in the profile directory,
|
|
and run the command using the option: --commandprofile ProfileName.
|
|
.
|
|
.SS Zeroing
|
|
.
|
|
When a thin pool provisions a new data block for a thin LV, the
|
|
new block is first overwritten with zeros. The zeroing mode is
|
|
indicated by the "z" attribute displayed by lvs. The option -Z
|
|
(or --zero) can be added to commands to specify the zeroing mode.
|
|
.P
|
|
Command to set the zeroing mode when creating a thin pool LV:
|
|
.P
|
|
.B lvconvert --type thin-pool -Z y|n
|
|
.RS
|
|
.B --poolmetadata VG/ThinMetaLV VG/ThinDataLV
|
|
.RE
|
|
.P
|
|
Command to change the zeroing mode of an existing thin pool LV:
|
|
.P
|
|
.B lvchange -Z y|n VG/ThinPoolLV
|
|
.P
|
|
If zeroing mode is changed from "n" to "y", previously provisioned
|
|
blocks are not zeroed.
|
|
.P
|
|
Provisioning of large zeroed chunks impacts performance.
|
|
.P
|
|
.BR lvm.conf (5)
|
|
.B thin_pool_zero
|
|
.br
|
|
controls the default zeroing mode used when creating a thin pool.
|
|
.
|
|
.SS Discard
|
|
.
|
|
The discard behavior of a thin pool LV determines how discard requests are
|
|
handled. Enabling discard under a file system may adversely affect the
|
|
file system performance (see the section on fstrim for an alternative.)
|
|
Possible discard behaviors:
|
|
.P
|
|
.B ignore:
|
|
Ignore any discards that are received.
|
|
.P
|
|
.B nopassdown:
|
|
Process any discards in the thin pool itself and allow
|
|
the no longer needed extents to be overwritten by new data.
|
|
.P
|
|
.B passdown:
|
|
Process discards in the thin pool (as with nopassdown), and
|
|
pass the discards down the the underlying device. This is the default
|
|
mode.
|
|
.P
|
|
Command to display the current discard mode of a thin pool LV:
|
|
.br
|
|
.B lvs -o+discards VG/ThinPoolLV
|
|
.P
|
|
Command to set the discard mode when creating a thin pool LV:
|
|
.br
|
|
.B lvconvert --discards ignore|nopassdown|passdown
|
|
.RS
|
|
.B --type thin-pool --poolmetadata VG/ThinMetaLV VG/ThinDataLV
|
|
.RE
|
|
.P
|
|
Command to change the discard mode of an existing thin pool LV:
|
|
.br
|
|
.B lvchange --discards ignore|nopassdown|passdown VG/ThinPoolLV
|
|
.P
|
|
.I Example
|
|
.nf
|
|
# lvs -o name,discards vg/pool0
|
|
pool0 passdown
|
|
.P
|
|
# lvchange --discards ignore vg/pool0
|
|
.fi
|
|
.P
|
|
.BR lvm.conf (5)
|
|
.B thin_pool_discards
|
|
.br
|
|
controls the default discards mode used when creating a thin pool.
|
|
.
|
|
.SS Chunk size
|
|
.
|
|
The size of data blocks managed by a thin pool can be specified with the
|
|
--chunksize option when the thin pool LV is created. The default unit
|
|
is KiB. The value must be a multiple of 64KiB between 64KiB and 1GiB.
|
|
.P
|
|
When a thin pool is used primarily for the thin provisioning feature, a
|
|
larger value is optimal. To optimize for many snapshots, a smaller value
|
|
reduces copying time and consumes less space.
|
|
.P
|
|
Command to display the thin pool LV chunk size:
|
|
.P
|
|
.B lvs -o+chunksize VG/ThinPoolLV
|
|
.P
|
|
.I Example
|
|
.nf
|
|
# lvs -o name,chunksize
|
|
pool0 64.00k
|
|
.fi
|
|
.P
|
|
.BR lvm.conf (5)
|
|
.B thin_pool_chunk_size
|
|
.br
|
|
controls the default chunk size used when creating a thin pool.
|
|
.P
|
|
The default value is shown by:
|
|
.br
|
|
.B lvmconfig --type default allocation/thin_pool_chunk_size
|
|
.P
|
|
.
|
|
.SS Size of pool metadata LV
|
|
.
|
|
The amount of thin metadata depends on how many blocks are shared between
|
|
thin LVs (i.e. through snapshots). A thin pool with many snapshots may
|
|
need a larger metadata LV. Thin pool metadata LV sizes can be from 2MiB
|
|
to approximately 16GiB.
|
|
.P
|
|
When using lvcreate to create what will become a thin metadata LV, the
|
|
size is specified with the -L|--size option.
|
|
.P
|
|
When an LVM command automatically creates a thin metadata LV, the size is
|
|
specified with the --poolmetadatasize option. When this option is not
|
|
given, LVM automatically chooses a size based on the data size and chunk
|
|
size.
|
|
.P
|
|
It can be hard to predict the amount of metadata space that will be
|
|
needed, so it is recommended to start with a size of 1GiB which should be
|
|
enough for all practical purposes. A thin pool metadata LV can later be
|
|
manually or automatically extended if needed.
|
|
.P
|
|
Configurable setting
|
|
.BR lvm.conf (5)
|
|
.BR allocation / thin_pool_crop_metadata
|
|
gives control over cropping to 15.81GiB to stay backward compatible with older
|
|
versions of lvm2. With enabled cropping there can be observed some problems when
|
|
using volumes above this size with thin tools (i.e. thin_repair).
|
|
Cropping should be enabled only when compatibility is required.
|
|
.
|
|
.SS Create a thin snapshot of an external, read only LV
|
|
.
|
|
Thin snapshots are typically taken of other thin LVs or other
|
|
thin snapshot LVs within the same thin pool. It is also possible
|
|
to take thin snapshots of external, read only LVs. Writes to the
|
|
snapshot are stored in the thin pool, and the external LV is used
|
|
to read unwritten parts of the thin snapshot.
|
|
.P
|
|
.B lvcreate -n SnapLV -s VG/ExternalOriginLV --thinpool VG/ThinPoolLV
|
|
.P
|
|
.I Example
|
|
.nf
|
|
# lvchange -an vg/lve
|
|
# lvchange --permission r vg/lve
|
|
# lvcreate -n snaplve -s vg/lve --thinpool vg/pool0
|
|
.P
|
|
# lvs vg/lve vg/snaplve
|
|
LV VG Attr LSize Pool Origin Data%
|
|
lve vg ori------- 10.00g
|
|
snaplve vg Vwi-a-tz-- 10.00g pool0 lve 0.00
|
|
.fi
|
|
.
|
|
.SS Convert a standard LV to a thin LV with an external origin
|
|
.
|
|
A new thin LV can be created and given the name of an existing
|
|
standard LV. At the same time, the existing LV is converted to a
|
|
read only external LV with a new name. Unwritten portions of the
|
|
thin LV are read from the external LV.
|
|
The new name given to the existing LV can be specified with
|
|
--originname, otherwise the existing LV will be given a default
|
|
name, e.g. lvol#.
|
|
.P
|
|
Convert ExampleLV into a read only external LV with the new name
|
|
NewExternalOriginLV, and create a new thin LV that is given the previous
|
|
name of ExampleLV.
|
|
.P
|
|
.B lvconvert --type thin --thinpool VG/ThinPoolLV
|
|
.RS
|
|
.B --originname NewExternalOriginLV VG/ExampleLV
|
|
.RE
|
|
.P
|
|
.I Example
|
|
.nf
|
|
# lvcreate -n lv_example -L 10G vg
|
|
.P
|
|
# lvs
|
|
lv_example vg -wi-a----- 10.00g
|
|
.P
|
|
# lvconvert --type thin --thinpool vg/pool0
|
|
--originname lv_external --thin vg/lv_example
|
|
.P
|
|
# lvs
|
|
LV VG Attr LSize Pool Origin
|
|
lv_example vg Vwi-a-tz-- 10.00g pool0 lv_external
|
|
lv_external vg ori------- 10.00g
|
|
.fi
|
|
.
|
|
.SS Single step thin pool LV creation
|
|
.
|
|
A thin pool LV can be created with a single lvcreate command,
|
|
rather than using lvconvert on existing LVs.
|
|
This one command creates a thin data LV, a thin metadata LV,
|
|
and combines the two into a thin pool LV.
|
|
.P
|
|
.B lvcreate --type thin-pool -L LargeSize -n ThinPoolLV VG
|
|
.P
|
|
.I Example
|
|
.nf
|
|
# lvcreate --type thin-pool -L8M -n pool0 vg
|
|
.P
|
|
# lvs vg/pool0
|
|
LV VG Attr LSize Pool Origin Data%
|
|
pool0 vg twi-a-tz-- 8.00m 0.00
|
|
.P
|
|
# lvs -a
|
|
pool0 vg twi-a-tz-- 8.00m
|
|
[pool0_tdata] vg Twi-ao---- 8.00m
|
|
[pool0_tmeta] vg ewi-ao---- 8.00m
|
|
.fi
|
|
.
|
|
.SS Single step thin pool LV and thin LV creation
|
|
.
|
|
A thin pool LV and a thin LV can be created with a single
|
|
lvcreate command. This one command creates a thin data LV,
|
|
a thin metadata LV, combines the two into a thin pool LV,
|
|
and creates a thin LV in the new pool.
|
|
.br
|
|
-L LargeSize specifies the physical size of the thin pool LV.
|
|
.br
|
|
-V VirtualSize specifies the virtual size of the thin LV.
|
|
.P
|
|
.B lvcreate --type thin -V VirtualSize -L LargeSize
|
|
.RS
|
|
.B -n ThinLV --thinpool VG/ThinPoolLV
|
|
.RE
|
|
.P
|
|
Equivalent to:
|
|
.br
|
|
.B lvcreate --type thin-pool -L LargeSize VG/ThinPoolLV
|
|
.br
|
|
.B lvcreate -n ThinLV -V VirtualSize --thinpool VG/ThinPoolLV
|
|
.P
|
|
.I Example
|
|
.nf
|
|
# lvcreate -L8M -V2G -n thin1 --thinpool vg/pool0
|
|
.P
|
|
# lvs -a
|
|
pool0 vg twi-a-tz-- 8.00m
|
|
[pool0_tdata] vg Twi-ao---- 8.00m
|
|
[pool0_tmeta] vg ewi-ao---- 8.00m
|
|
thin1 vg Vwi-a-tz-- 2.00g pool0
|
|
.fi
|
|
.
|
|
.SS Merge thin snapshots
|
|
.
|
|
A thin snapshot can be merged into its origin thin LV using the lvconvert
|
|
--merge command. The result of a snapshot merge is that the origin thin
|
|
LV takes the content of the snapshot LV, and the snapshot LV is removed.
|
|
Any content that was unique to the origin thin LV is lost after the merge.
|
|
.P
|
|
Because a merge changes the content of an LV, it cannot be done while the
|
|
LVs are open, e.g. mounted. If a merge is initiated while the LVs are open,
|
|
the effect of the merge is delayed until the origin thin LV is next
|
|
activated.
|
|
.P
|
|
.B lvconvert --merge VG/SnapLV
|
|
.P
|
|
.I Example
|
|
.nf
|
|
# lvs vg
|
|
LV VG Attr LSize Pool Origin
|
|
pool0 vg twi-a-tz-- 10.00g
|
|
thin1 vg Vwi-a-tz-- 100.00g pool0
|
|
thin1s1 vg Vwi-a-tz-k 100.00g pool0 thin1
|
|
.P
|
|
# lvconvert --merge vg/thin1s1
|
|
.P
|
|
# lvs vg
|
|
LV VG Attr LSize Pool Origin
|
|
pool0 vg twi-a-tz-- 10.00g
|
|
thin1 vg Vwi-a-tz-- 100.00g pool0
|
|
.fi
|
|
.P
|
|
.I Example
|
|
.nf
|
|
Delayed merging of open LVs.
|
|
.P
|
|
# lvs vg
|
|
LV VG Attr LSize Pool Origin
|
|
pool0 vg twi-a-tz-- 10.00g
|
|
thin1 vg Vwi-aotz-- 100.00g pool0
|
|
thin1s1 vg Vwi-aotz-k 100.00g pool0 thin1
|
|
.P
|
|
# df
|
|
/dev/mapper/vg-thin1 100G 33M 100G 1% /mnt/X
|
|
/dev/mapper/vg-thin1s1 100G 33M 100G 1% /mnt/Xs
|
|
.P
|
|
# ls /mnt/X
|
|
file1 file2 file3
|
|
# ls /mnt/Xs
|
|
file3 file4 file5
|
|
.P
|
|
# lvconvert --merge vg/thin1s1
|
|
Logical volume vg/thin1s1 contains a filesystem in use.
|
|
Delaying merge since snapshot is open.
|
|
Merging of thin snapshot thin1s1 will occur on next activation.
|
|
.P
|
|
# umount /mnt/X
|
|
# umount /mnt/Xs
|
|
.P
|
|
# lvs -a vg
|
|
LV VG Attr LSize Pool Origin
|
|
pool0 vg twi-a-tz-- 10.00g
|
|
[pool0_tdata] vg Twi-ao---- 10.00g
|
|
[pool0_tmeta] vg ewi-ao---- 1.00g
|
|
thin1 vg Owi-a-tz-- 100.00g pool0
|
|
[thin1s1] vg Swi-a-tz-k 100.00g pool0 thin1
|
|
.P
|
|
# lvchange -an vg/thin1
|
|
# lvchange -ay vg/thin1
|
|
.P
|
|
# mount /dev/vg/thin1 /mnt/X
|
|
.P
|
|
# ls /mnt/X
|
|
file3 file4 file5
|
|
.fi
|
|
.
|
|
.SS XFS on snapshots
|
|
.
|
|
Mounting an XFS file system on a new snapshot LV requires attention to the
|
|
file system's log state and uuid. On the snapshot LV, the xfs log will
|
|
contain a dummy transaction, and the xfs uuid will match the uuid from the
|
|
file system on the origin LV.
|
|
.P
|
|
If the snapshot LV is writable, mounting will recover the log to clear the
|
|
dummy transaction, but will require skipping the uuid check:
|
|
.P
|
|
# mount /dev/VG/SnapLV /mnt -o nouuid
|
|
.P
|
|
After the first mount with the above approach, the UUID can subsequently be
|
|
changed using:
|
|
.P
|
|
# xfs_admin -U generate /dev/VG/SnapLV
|
|
.P
|
|
# mount /dev/VG/SnapLV /mnt
|
|
.P
|
|
Once the UUID has been changed, the mount command will no longer require
|
|
the nouuid option.
|
|
.P
|
|
If the snapshot LV is readonly, the log recovery and uuid check need to be
|
|
skipped while mounting readonly:
|
|
.P
|
|
# mount /dev/VG/SnapLV /mnt -o ro,nouuid,norecovery
|
|
.
|
|
.SH SEE ALSO
|
|
.
|
|
.nh
|
|
.ad l
|
|
.BR lvm (8),
|
|
.BR lvm.conf (5),
|
|
.BR lvmconfig (8),
|
|
.BR lvcreate (8),
|
|
.BR lvconvert (8),
|
|
.BR lvchange (8),
|
|
.BR lvextend (8),
|
|
.BR lvremove (8),
|
|
.BR lvs (8),
|
|
.P
|
|
.BR thin_dump (8),
|
|
.BR thin_repair (8),
|
|
.BR thin_restore (8)
|