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| author | Mike Snitzer <snitzer@redhat.com> | 2010-08-20 20:59:05 +0000 |
|---|---|---|
| committer | Mike Snitzer <snitzer@redhat.com> | 2010-08-20 20:59:05 +0000 |
| commit | 4efb1d9cbbd8d38e2462cd76b9bb1b247e5b549c (patch) | |
| tree | 7663aac7886dbc0af9cd6070bd4f6fe0d8250a87 /doc/example.conf.in | |
| parent | aa06d919727e770b056ec59c48147d0bd1bbfe70 (diff) | |
| download | lvm2-4efb1d9cbbd8d38e2462cd76b9bb1b247e5b549c.tar.gz lvm2-4efb1d9cbbd8d38e2462cd76b9bb1b247e5b549c.tar.xz lvm2-4efb1d9cbbd8d38e2462cd76b9bb1b247e5b549c.zip | |
Update heuristic used for default and detected data alignment.
Add "devices/default_data_alignment" to lvm.conf to control the internal
default that LVM2 uses: 0==64k, 1==1MB, 2==2MB, etc.
If --dataalignment (or lvm.conf's "devices/data_alignment") is specified
then it is always used to align the start of the data area. This means
the md_chunk_alignment and data_alignment_detection are disabled if set.
(Same now applies to pvcreate --dataalignmentoffset, the specified value
will be used instead of the result from data_alignment_offset_detection)
set_pe_align() still looks to use the determined default alignment
(based on lvm.conf's default_data_alignment) if the default is a
multiple of the MD or topology detected values.
Diffstat (limited to 'doc/example.conf.in')
| -rw-r--r-- | doc/example.conf.in | 12 |
1 files changed, 9 insertions, 3 deletions
diff --git a/doc/example.conf.in b/doc/example.conf.in index 7edae715..6c75f8c9 100644 --- a/doc/example.conf.in +++ b/doc/example.conf.in @@ -98,6 +98,11 @@ devices { # 1 enables; 0 disables. md_chunk_alignment = 1 + # Default alignment of the start of a data area in MB. If set to 0, + # a small value of 64KB will be used, which was the default until + # LVM2 version 2.02.73. Set to 1 for 1MiB, 2 for 2MiB, etc. + default_data_alignment = 1 + # By default, the start of a PV's data area will be a multiple of # the 'minimum_io_size' or 'optimal_io_size' exposed in sysfs. # - minimum_io_size - the smallest request the device can perform @@ -111,9 +116,9 @@ devices { data_alignment_detection = 1 # Alignment (in KB) of start of data area when creating a new PV. - # If a PV is placed directly upon an md device and md_chunk_alignment or - # data_alignment_detection is enabled this parameter is ignored. - # Set to 0 for the default alignment of 1MB or page size, if larger. + # md_chunk_alignment and data_alignment_detection are disabled if set. + # Set to 0 for the default alignment (see: data_alignment_default) + # or page size, if larger. data_alignment = 0 # By default, the start of the PV's aligned data area will be shifted by @@ -122,6 +127,7 @@ devices { # windows partitioning will have an alignment_offset of 3584 bytes # (sector 7 is the lowest aligned logical block, the 4KB sectors start # at LBA -1, and consequently sector 63 is aligned on a 4KB boundary). + # But note that pvcreate --dataalignmentoffset will skip this detection. # 1 enables; 0 disables. data_alignment_offset_detection = 1 |