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b73de73151
Add basic support for converting LV into an external origin volume. Syntax: lvconvert --thinpool vg/pool --originname renamed_origin -T origin It will convert volume 'origin' into a thin volume, which will use 'renamed_origin' as an external read-only origin. All read/write into origin will go via 'pool'. renamed_origin volume is read-only volume, that could be activated only in read-only mode, and cannot be modified.
425 lines
16 KiB
Groff
425 lines
16 KiB
Groff
.TH LVCONVERT 8 "LVM TOOLS #VERSION#" "Red Hat, Inc" \" -*- nroff -*-
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.SH NAME
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lvconvert \- convert a logical volume from linear to mirror or snapshot
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.SH SYNOPSIS
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.B lvconvert
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.BR \-m | \-\-mirrors
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.I Mirrors
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.RB [ \-\-mirrorlog
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.RI { disk | core | mirrored }]
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.RB [ \-\-corelog ]
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.RB [ \-R | \-\-regionsize
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.IR MirrorLogRegionSize ]
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.RB [ \-\-type
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.IR SegmentType ]
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.RB [ \-A | \-\-alloc
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.IR AllocationPolicy ]
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.RB [ \-b | \-\-background ]
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.RB [ \-f | \-\-force ]
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.RB [ \-i | \-\-interval
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.IR Seconds ]
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.RB [ \-h | \-? | \-\-help ]
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.RB [ \-\-stripes
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.I Stripes
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.RB [ \-I | \-\-stripesize
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.IR StripeSize ]]
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.RB [ \-\-noudevsync ]
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.RB [ \-v | \-\-verbose ]
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.RB [ \-y | \-\-yes ]
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.RB [ \-\-version ]
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.IR LogicalVolume [ Path ]
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.RI [ PhysicalVolume [ Path ][ :PE [ -PE ]]...]
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.sp
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.B lvconvert \-\-splitmirrors \fIImages
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.RB [ \-\-name
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.IR SplitLogicalVolumeName ]
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.RB [ \-\-trackchanges ]
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.IR MirrorLogicalVolume [ Path ]
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.RI [ SplittablePhysicalVolume [ Path ][ :PE [ -PE ]]...]
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.sp
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.B lvconvert
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.BR \-s | \-\-snapshot
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.RB [ \-c | \-\-chunksize
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.IR ChunkSize [ bBsSkK ]]
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.RB [ \-h | \-? | \-\-help ]
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.RB [ \-\-noudevsync ]
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.RB [ \-v | \-\-verbose ]
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.RB [ \-Z | \-\-zero
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.RI { y | n }]
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.RB [ \-\-version ]
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.IR OriginalLogicalVolume [ Path ]
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.IR SnapshotLogicalVolume [ Path ]
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.sp
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.B lvconvert \-\-merge
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.RB [ \-b | \-\-background ]
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.RB [ \-i | \-\-interval
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.IR Seconds ]
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.RB [ \-h | \-? | \-\-help ]
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.RB [ \-v | \-\-verbose ]
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.RB [ \-\-version ]
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.IR LogicalVolume [ Path ]...
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.sp
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.B lvconvert \-\-repair
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.RB [ \-h | \-? | \-\-help ]
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.RB [ \-\-stripes
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.I Stripes
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.RB [ \-I | \-\-stripesize
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.IR StripeSize ]]
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.RB [ \-v | \-\-verbose ]
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.RB [ \-\-version ]
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.IR LogicalVolume [ Path ]
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.RI [ PhysicalVolume [ Path ]...]
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.sp
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.B lvconvert \-\-replace \fIPhysicalVolume
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.RB [ \-h | \-? | \-\-help ]
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.RB [ \-v | \-\-verbose ]
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.RB [ \-\-version ]
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.IR LogicalVolume [ Path ]
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.RI [ PhysicalVolume [ Path ]...]
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.sp
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.B lvconvert \-\-thinpool
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.IR ThinPoolLogicalVolume { Name | Path }
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.RB [ \-c | \-\-chunksize
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.IR ChunkSize [ bBsSkKmMgG ]]
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.RB [ \-\-discards
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.RI { ignore | nopassdown | passdown }]
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.RB [[ \-\-poolmetadata
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.IR ThinPoolMetadataLogicalVolume { Name | Path }]
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.RB [ \-\-poolmetadatasize
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.IR ThinPoolMetadataSize [ bBsSkKmMgG ]]
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.RB [ \-r | \-\-readahead
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.RI { ReadAheadSectors | auto | none }]
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.RB [ \-\-stripes
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.I Stripes
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.RB [ \-I | \-\-stripesize
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.IR StripeSize ]]]
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.RB [ \-Z | \-\-zero
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.RI { y | n }]
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.RB [ \-h | \-? | \-\-help ]
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.RB [ \-v | \-\-verbose ]
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.RB [ \-\-version ]
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.RB [ \-T | \-\-thin
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.IR ExternalOriginLogicalVolume { Name | Path }
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.RB [ \-\-originname
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.IR NewExternalOriginVolumeName ]]
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.RI [ PhysicalVolume [ Path ][ :PE [ -PE ]]...]
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.sp
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.SH DESCRIPTION
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lvconvert is used to change the segment type (i.e. linear, mirror, etc) or
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characteristics of a logical volume. For example, it can add or remove the
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redundant images of a logical volume, change the log type of a mirror, or
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designate a logical volume as a snapshot repository.
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.br
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If the conversion requires allocation of physical extents (for
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example, when converting from linear to mirror) and you specify
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one or more PhysicalVolumes (optionally with ranges of physical
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extents), allocation of physical extents will be restricted to
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these physical extents. If the conversion frees physical extents
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(for example, when converting from a mirror to a linear, or reducing
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mirror legs) and you specify one or more PhysicalVolumes,
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the freed extents come first from the specified PhysicalVolumes.
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.SH OPTIONS
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See \fBlvm\fP(8) for common options.
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.br
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Exactly one of
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.BR \-\-merge ", " \-\-mirrors ", " \-\-repair ", " \-\-replace
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.RB ", " \-\-snapshot ", " \-\-splitmirrors " or " \-\-thinpool
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arguments is required.
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.TP
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.BR \-m ", " \-\-mirrors " " \fIMirrors
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Specifies the degree of the mirror you wish to create.
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For example, "\fB-m 1\fP" would convert the original logical
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volume to a mirror volume with 2-sides; that is, a
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linear volume plus one copy.
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.TP
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.IR \fB\-\-mirrorlog " {" disk | core | mirrored }
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Specifies the type of log to use.
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The default is disk, which is persistent and requires
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a small amount of storage space, usually on a separate device
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from the data being mirrored.
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Core may be useful for short-lived mirrors: It means the mirror is
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regenerated by copying the data from the first device again every
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time the device is activated - perhaps, for example, after every reboot.
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Using "mirrored" will create a persistent log that is itself mirrored.
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.TP
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.B \-\-corelog
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The optional argument \fB--corelog\fP is the same as specifying
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\fB--mirrorlog core\fP.
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.TP
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.BR \-R ", " \-\-regionsize " " \fIMirrorLogRegionSize
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A mirror is divided into regions of this size (in MB), and the mirror log
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uses this granularity to track which regions are in sync.
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.TP
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.B \-\-type \fISegmentType
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Used to convert a logical volume to another segment type or to explicitly state
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the desired RAID1 segment type (\fImirror\fP or \fIraid1\fP) when converting
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a linear logical volume to a mirror with the \fB-m\fP argument.
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.TP
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.BR \-b ", " \-\-background
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Run the daemon in the background.
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.TP
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.BR \-i ", " \-\-interval " " \fISeconds
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Report progress as a percentage at regular intervals.
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.TP
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.B \-\-noudevsync
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Disable udev synchronisation. The
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process will not wait for notification from udev.
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It will continue irrespective of any possible udev processing
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in the background. You should only use this if udev is not running
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or has rules that ignore the devices LVM2 creates.
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.TP
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.B \-\-splitmirrors \fIImages
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The number of redundant Images of a mirror to be split off and used
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to form a new logical volume. A name must be supplied for the
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newly-split-off logical volume using the \fB\-\-name\fP argument, unless
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the \fB\-\-trackchanges\fP argument is given.
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.TP
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.B \-n \fIName
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The name to apply to a logical volume which has been split off from
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a mirror logical volume.
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.TP
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.B \-\-trackchanges
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Used with \fB\-\-splitmirrors\fP on a raid1 device, this tracks changes so
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that the read-only detached image can be merged efficiently back into
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the mirror later. Only the regions of the detatched device where
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the data changed get resynchronized.
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Please note that this feature is only supported with the new md-based mirror
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implementation and not with the original device-mapper mirror implementation.
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.TP
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.B \-s, \-\-snapshot
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Create a snapshot from existing logical volume using another
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existing logical volume as its origin.
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.TP
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.BR \-c ", " \-\-chunksize " " \fIChunkSize [ \fIbBsSkKmMgG ]
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Gives the size of chunk for snapshot and thin pool logical volumes.
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For snapshots the value must be power of 2 between 4KiB and 512KiB
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and the default value is 4.
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For thin pools the value must be between 64KiB and
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1GiB and the default value starts with 64 and scales
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up to fit the pool metadata size within 128MB,
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if the pool metadata size is not specified.
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Older dm thin pool target version (<1.4) requires the value to be power of 2.
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The newer version requires to be the multiple of 64KiB, however discard is
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not supported for non power of 2 values.
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Default unit is in kilobytes.
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.TP
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.BR \-\-discards " {" \fIignore | \fInopassdown | \fIpassdown }
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Sets discards behavior for thin pool.
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Default is \fIpassdown\fP.
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.TP
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.BR \-Z ", " \-\-zero " {" \fIy | \fIn }
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Controls zeroing of the first KB of data in the snapshot.
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If the volume is read-only the snapshot will not be zeroed.
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For thin pool volumes it controls zeroing of provisioned blocks.
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Note: Provisioning of large zeroed chunks impacts performance.
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.TP
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.B \-\-merge
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Merges a snapshot into its origin volume or merges a raid1 image that has
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been split from its mirror with \fB\-\-trackchanges\fP back into its mirror.
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To check if your kernel supports the snapshot merge feature, look
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for 'snapshot-merge' in the output
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of \fBdmsetup targets\fP. If both the origin and snapshot volume are not
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open the merge will start immediately. Otherwise, the merge will start
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the first time either the origin or snapshot are activated and both are closed.
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Merging a snapshot into an origin that cannot be closed, for example a root
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filesystem, is deferred until the next time the origin volume is activated.
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When merging starts, the resulting logical volume will have the origin's name,
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minor number and UUID. While the merge is in progress, reads or writes to the
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origin appear as they were directed to the snapshot being merged. When the
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merge finishes, the merged snapshot is removed. Multiple snapshots may
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be specified on the commandline or a @tag may be used to specify
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multiple snapshots be merged to their respective origin.
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.TP
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.B \-\-originname \fINewExternalOriginVolumeName\fP
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The name for converted external origin volume.
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.br
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Without this option a default names of "lvol#" will be generated where
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# is the LVM internal number of the logical volume.
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Converted volume will be read-only.
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.TP
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.BR \-\-poolmetadata " " \fIThinPoolMetadataLogicalVolume { \fIName | \fIPath }
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Specifies thin pool metadata logical volume.
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The size should be in between 2MiB and 16GiB.
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Thin pool is specified with the option
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\fB\-\-thinpool\fP.
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When the specified thin pool already exists,
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the thin pool's metadata volume will be swapped with the given LV.
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Properties of the thin pool like chunk size, discards or zero
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are preserved by default in this case.
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It can be useful for thin pool metadata repair or its offline resize,
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since the content of metadata becomes accessible for
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thin provisioning tools \fBthin_dump\fP(8) and \fBthin_restore\fP(8).
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.TP
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.BR \-\-poolmetadatasize " " \fIThinPoolMetadataSize [ \fIbBsSkKmMgG ]
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Sets the size of thin pool's metadata logical volume,
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if the pool metadata volume is undefined.
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Thin pool is specified with the option
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\fB\-\-thinpool\fP.
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Supported value is in the range between 2MiB and 16GiB.
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The default value is estimated with this formula
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(Pool_LV_size / Pool_LV_chunk_size * 64b).
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Default unit is megabytes.
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.TP
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.IR \fB\-r ", " \fB\-\-readahead " {" ReadAheadSectors | auto | none }
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Sets read ahead sector count of thin pool metadata logical volume.
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The default value is "auto" which allows the kernel to choose
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a suitable value automatically.
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"None" is equivalent to specifying zero.
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.TP
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.B \-\-repair
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Repair a mirror after suffering a disk failure. The mirror will be brought back
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into a consistent state. By default, the original number of mirrors will be
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restored if possible. Specify \fB\-y\fP on the command line to skip
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the prompts. Use \fB\-f\fP if you do not want any replacement.
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Additionally, you may use \fB\-\-use-policies\fP to use the device
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replacement policy specified in \fBlvm.conf\fP(5),
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viz. activation/mirror_log_fault_policy or
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activation/mirror_device_fault_policy.
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.TP
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.B \-\-replace \fIPhysicalVolume
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Remove the specified device (\fIPhysicalVolume\fP) and replace it with one
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that is available in the volume group or from the specific list provided.
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This option is only available to RAID segment types
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(e.g. "raid1", "raid5", etc).
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.TP
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.BR \-\-stripes " " \fIStripes
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Gives the number of stripes.
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This is equal to the number of physical volumes to scatter
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the logical volume. This does not apply to existing allocated
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space, only newly allocated space can be striped.
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.TP
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.BR \-I ", " \-\-stripesize " " \fIStripeSize
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Gives the number of kilobytes for the granularity of the stripes.
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.br
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StripeSize must be 2^n (n = 2 to 9) for metadata in LVM1 format.
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For metadata in LVM2 format, the stripe size may be a larger
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power of 2 but must not exceed the physical extent size.
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.TP
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.IR \fB\-T ", " \fB\-\-thin " " ExternalOriginLogicalVolume { Name | Path }
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Changes the logical volume into a thin volume for the thin pool
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specified with the option \fB\-\-thinpool\fP. \fIExternalOriginLogicalVolume\fP
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is converted into a new read-only logical volume which will be used as an
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external origin volume for unprovisioned areas.
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The non-default name for this new volume can be specified with \fB\-\-originname\fP.
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.TP
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.IR \fB\-\-thinpool " " ThinPoolLogicalVolume { Name | Path }
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Changes logical volume into a thin pool volume. The volume
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will store the pool's data.
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Thin pool metadata logical volume can be specified with the option
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\fB\-\-poolmetadata\fP or allocated with \fB\-\-poolmetadatasize\fP.
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.SH Examples
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Converts the linear logical volume "vg00/lvol1" to a two-way mirror
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logical volume:
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.sp
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.B lvconvert \-m1 vg00/lvol1
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Converts the linear logical volume "vg00/lvol1" to a two-way RAID1
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logical volume:
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.sp
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.B lvconvert \-\-type raid1 \-m1 vg00/lvol1
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Converts a mirror with a disk log to a mirror with an in-memory log:
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.sp
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.B lvconvert \-\-mirrorlog core vg00/lvol1
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Converts a mirror with an in-memory log to a mirror with a disk log:
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.sp
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.B lvconvert \-\-mirrorlog disk vg00/lvol1
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Converts a mirror logical volume to a linear logical volume:
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.sp
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.B lvconvert \-m0 vg00/lvol1
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Converts a mirror logical volume to a RAID1 logical volume with the same
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number of images:
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.sp
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.B lvconvert \-\-type raid1 vg00/mirror_lv
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Converts logical volume "vg00/lvol2" to snapshot of original volume
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"vg00/lvol1":
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.sp
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.B lvconvert \-s vg00/lvol1 vg00/lvol2
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Converts linear logical volume "vg00/lvol1" to a two-way mirror,
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using physical extents /dev/sda:0-15 and /dev/sdb:0-15 for allocation
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of new extents:
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.sp
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.B lvconvert \-m1 vg00/lvol1 /dev/sda:0-15 /dev/sdb:0-15
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Converts mirror logical volume "vg00/lvmirror1" to linear, freeing physical
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extents from /dev/sda:
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.sp
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.B lvconvert \-m0 vg00/lvmirror1 /dev/sda
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Merges "vg00/lvol1_snap" into its origin:
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.sp
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.B lvconvert \-\-merge vg00/lvol1_snap
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If "vg00/lvol1", "vg00/lvol2" and "vg00/lvol3" are all tagged with "some_tag"
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each snapshot logical volume will be merged serially,
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e.g.: "vg00/lvol1", then "vg00/lvol2", then "vg00/lvol3".
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If \-\-background were used it would start
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all snapshot logical volume merges in parallel.
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.sp
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.B lvconvert \-\-merge @some_tag
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Extracts one image from the mirror, making it a new logical volume named
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"lv_split". The mirror the image is extracted from is reduced accordingly.
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If it was a 2-way mirror (created with '-m 1'), then the resulting original
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volume will be linear.
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.sp
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.B lvconvert \-\-splitmirrors 1 \-\-name lv_split vg00/lvmirror1
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A mirrored logical volume created with \-\-type raid1 can use the
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\-\-trackchanges argument when splitting off an image.
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Detach one image from the mirrored logical volume lv_raid1 as a separate
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read-only device and track the changes made to the mirror while it is detached.
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The split-off device has a name of the form lv_raid1_rimage_N, where N is
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a number, and it cannot be renamed.
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.sp
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.B lvconvert \-\-splitmirrors 1 \-\-trackchanges vg00/lv_raid1
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Merge an image that was detached temporarily from its mirror with
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the \-\-trackchanges argument back into its original mirror and
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bring its contents back up-to-date.
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.sp
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.B lvconvert \-\-merge vg00/lv_raid1_rimage_1
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Replaces the physical volume "/dev/sdb1" in the RAID1 logical volume "my_raid1"
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with the specified physical volume "/dev/sdf1". Had the argument "/dev/sdf1"
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been left out, lvconvert would attempt to find a suitable device from those
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available in the volume group.
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.sp
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.B lvconvert \-\-replace /dev/sdb1 vg00/my_raid1 /dev/sdf1
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Convert the logical volume "vg00/lvpool" into a thin pool with chunk size 128KiB
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and convert "vg00/lv1" into a thin volume using this pool. Original "vg00/lv1"
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is used as an external read-only origin, where all writes to such volume
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are stored in the "vg00/lvpool".
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.sp
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.B lvconvert \-\-thinpool vg00/lvpool -c 128 -T lv1
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Convert the logical volume "vg00/origin" into a thin volume from the thin pool
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"vg00/lvpool". This thin volume will use "vg00/origin" as an external origin
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volume for unprovisioned areas in this volume.
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For the read-only external origin use the new name "vg00/external".
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.sp
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.B lvconvert \-\-thinpool vg00/lvpool \-\-originname external -T vg00/origin
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.SH SEE ALSO
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.BR lvm (8),
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.BR vgcreate (8),
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.BR lvremove (8),
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.BR lvrename (8),
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.BR lvextend (8),
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.BR lvreduce (8),
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.BR lvdisplay (8),
|
|
.BR lvscan (8),
|
|
.BR thin_dump(8),
|
|
.BR thin_restore(8)
|