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author | David Teigland <teigland@redhat.com> | 2015-05-27 15:53:01 -0500 |
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committer | David Teigland <teigland@redhat.com> | 2015-05-27 15:53:01 -0500 |
commit | 3225f8d17596b79b76ed9da5291843d02a2aa7b6 (patch) | |
tree | b5b760ba76ca7c01791d025dc8f4e355b2be190d | |
parent | 778b66a7199b5fe05d59df55bd23e681759c2bbe (diff) | |
download | lvm2-3225f8d17596b79b76ed9da5291843d02a2aa7b6.tar.gz |
man: lvmthin chunk and metadata sizes
Clear some stale information, and give a suggestion to use
a metadata size of 1GiB.
-rw-r--r-- | man/lvmthin.7.in | 54 |
1 files changed, 30 insertions, 24 deletions
diff --git a/man/lvmthin.7.in b/man/lvmthin.7.in index 79ca40ac3..eb791f089 100644 --- a/man/lvmthin.7.in +++ b/man/lvmthin.7.in @@ -907,12 +907,12 @@ autoextend the LV by this much additional space. To see the default values of these settings, run: -.B lvmconfig --type default --withcomment +.B lvmconfig \-\-type default \-\-withcomment .RS .B activation/thin_pool_autoextend_threshold .RE -.B lvmconfig --type default --withcomment +.B lvmconfig \-\-type default \-\-withcomment .RS .B activation/thin_pool_autoextend_percent .RE @@ -973,7 +973,7 @@ file with the profile also needs to be moved. .IP \[bu] 2 Only certain settings can be used in a VG or LV profile, see: .br -.B lvmconfig --type profilable-metadata. +.B lvmconfig \-\-type profilable-metadata. .IP \[bu] 2 An LV without a profile of its own will inherit the VG profile. @@ -986,9 +986,9 @@ Remove a profile from an LV using the command: .IP \[bu] 2 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 +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. +and run the command using the option: \-\-commandprofile ProfileName. .SS Zeroing @@ -1076,14 +1076,13 @@ controls the default discards mode used when creating a thin pool. \& -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 kilobytes and the default value is 64KiB. The value must be a -power of two between 4KiB and 1GiB. +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. -When a thin pool is used primarily for the thin provisioning feature, -a larger value is optimal. To optimize for a lot of snapshotting, -a smaller value reduces copying time and consumes less space. +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. Command to display the thin pool LV chunk size: .br @@ -1101,25 +1100,32 @@ Command to display the thin pool LV chunk size: .br controls the default chunk size used when creating a thin pool. +The default value is shown by: +.br +.B lvmconfig \-\-type default allocation/thin_pool_chunk_size + .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. +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 16GiB. -The range of supported metadata LV sizes is 2MiB to 16GiB. -.br -The default size is estimated with the formula: -.br -ThinPoolLVSize / ThinPoolLVChunkSize * 64b. +When using lvcreate to create what will become a thin metadata LV, the +size is specified with the \-L|\-\-size option. + +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. -When creating a thin metadata LV explicitly, the size is specified -in the lvcreate command. When a command automatically creates a -thin metadata LV, the \-\-poolmetadatasize option can be used specify -a non-default size. The default unit is megabytes. +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. .SS Create a thin snapshot of an external, read only LV |