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36cac41115
Commitsa29bb6a14b...5c199d99f4narrowed down on addressing the escaping of hyphens in the dynamic creation of manuals whilst avoiding them in creating help texts. This lead to a sequence of slipping through hyphens adrressed by additional patches in aforementioned commit series. On the other hand, postprocessing dynamically man-generator created and statically provided manuals catches all hyphens in need of escaping. Changes: - revert the above commits whilst keeping man-generator streamlining and the detection of any '\' when generating help texts in order to avoid escapes to slip in - Dynamically escape hyphens in manaual pages using sed(1) in the respective Makefile targets - remove any manually added escaping on hyphens from any static manual sources or headers
65 lines
2.7 KiB
Plaintext
65 lines
2.7 KiB
Plaintext
lvconvert changes the LV type and includes utilities for LV data
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maintenance. The LV type controls data layout and redundancy.
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The LV type is also called the segment type or segtype.
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To display the current LV type, run the command:
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.B lvs -o name,segtype
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.I LV
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The
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.B linear
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type is equivalent to the
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.B striped
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type when one stripe exists.
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In that case, the types can sometimes be used interchangably.
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In most cases, the
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.B mirror
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type is deprecated and the
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.B raid1
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type should be used. They are both implementations of mirroring.
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In some cases, an LV is a single device mapper (dm) layer above physical
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devices. In other cases, hidden LVs (dm devices) are layered between the
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visible LV and physical devices. LVs in the middle layers are called sub LVs.
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A command run on a visible LV sometimes operates on a sub LV rather than
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the specified LV. In other cases, a sub LV must be specified directly on
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the command line.
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Striped raid types are
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.B raid0/raid0_meta
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,
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.B raid5
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(an alias for raid5_ls),
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.B raid6
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(an alias for raid6_zr) and
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.B raid10
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(an alias for raid10_near).
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As opposed to mirroring, raid5 and raid6 stripe data and calculate parity
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blocks. The parity blocks can be used for data block recovery in case devices
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fail. A maximum number of one device in a raid5 LV may fail and two in case
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of raid6. Striped raid types typically rotate the parity blocks for performance
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reasons thus avoiding contention on a single device. Layouts of raid5 rotating
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parity blocks can be one of left-asymmetric (raid5_la), left-symmetric (raid5_ls
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with alias raid5), right-asymmetric (raid5_ra), right-symmetric (raid5_rs) and raid5_n,
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which doesn't rotate parity blocks. Any \"_n\" layouts allow for conversion between
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raid levels (raid5_n -> raid6 or raid5_n -> striped/raid0/raid0_meta).
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raid6 layouts are zero-restart (raid6_zr with alias raid6), next-restart (raid6_nr),
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next-continue (raid6_nc). Additionally, special raid6 layouts for raid level conversions
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between raid5 and raid6 are raid6_ls_6, raid6_rs_6, raid6_la_6 and raid6_ra_6. Those
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correspond to their raid5 counterparts (e.g. raid5_rs can be directly converted to raid6_rs_6
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and vice-versa).
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raid10 (an alias for raid10_near) is currently limited to one data copy and even number of
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sub LVs. This is a mirror group layout thus a single sub LV may fail per mirror group
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without data loss.
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Striped raid types support converting the layout, their stripesize
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and their number of stripes.
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The striped raid types combined with raid1 allow for conversion from linear -> striped/raid0/raid0_meta
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and vice-versa by e.g. linear <-> raid1 <-> raid5_n (then adding stripes) <-> striped/raid0/raid0_meta.
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Sub LVs can be displayed with the command
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.B lvs -a
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