btrfs-progs: docs: mount options, enhance ssd/nossd

Reported-by: Hans van Kranenburg <hans.van.kranenburg@mendix.com>
Signed-off-by: David Sterba <dsterba@suse.com>
This commit is contained in:
David Sterba 2017-03-31 19:40:05 +02:00
parent bd0ab27afb
commit 4a1d07e8c3

View File

@ -348,19 +348,20 @@ If a version is not explicitly specified, the default implementation will be
chosen, which is 'v1' as of 4.9.
*ssd*::
*nossd*::
*ssd_spread*::
*nossd*::
(default: SSD autodetected)
+
Options to control SSD allocation schemes. By default, BTRFS will
enable or disable SSD allocation heuristics depending on whether a
rotational or non-rotational disk is in use (contents of
'/sys/block/DEV/queue/rotational'). The 'ssd' and 'nossd' options
can override this autodetection.
rotational or non-rotational device is in use (contents of
'/sys/block/DEV/queue/rotational'). If it is, the 'ssd' option is turned on.
The option 'nossd' will disable the autodetection.
+
The 'ssd_spread' mount option attempts to allocate into bigger and aligned
chunks of unused space, and may perform better on low-end SSDs. 'ssd_spread'
implies 'ssd', enabling all other SSD heuristics as well.
implies 'ssd', enabling all other SSD heuristics as well. The option 'nossd'
will disable all SSD options.
*subvol='path'*::
Mount subvolume from 'path' rather than the toplevel subvolume. The