RepoMirrors/btrfs-progs
1
0
Fork 0
mirror of https://github.com/kdave/btrfs-progs synced 2025-04-27 13:37:56 +00:00
Code Issues Packages Projects Releases Wiki Activity

btrfs-progs: docs: man5, add space_cache=v2

Browse Source 
Signed-off-by: David Sterba <dsterba@suse.com>
This commit is contained in:
David Sterba 2016-03-17 14:49:32 +01:00
parent 974d2ed564
commit 40dc7c504c
1 changed files with 17 additions and 5 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

22
Documentation/btrfs-man5.asciidoc
View File

@ -278,13 +278,25 @@ May be resumed with *btrfs balance resume* or the paused state can be removed
by *btrfs balance cancel*.
*space_cache*::
*space_cache=v2*::
*nospace_cache*::
('nospace_cache' since: 3.2, default: on)
('nospace_cache' since: 3.2, 'space_cache=v2' since 4.5, default: on)
+
Disable freespace cache loading without clearing the cache and the free space
cache will not be used during the mount. This affects performance as searching
for new free blocks could take longer. On the other hand, managing the space
cache consumes some resources.
Options to control the free space cache. This affects performance as searching
for new free blocks could take longer if the space cache is not enabled. On the
other hand, managing the space cache consumes some resources. It can be
disabled without clearing at mount time.
+
There are two implementations of how the space is tracked. The safe default is
'v1'. On large filesystems (many-terabytes) and certain workloads the 'v1'
performance may degrade. This problem is addressed by 'v2', that is based on
b-trees, sometimes referred to as 'free-space-tree'.
+
'Compatibility notes:'
+
* the 'v2' has to be enabled manually at mount time, once
* kernel without 'v2' support will be able to mount the filesystem in read-only mode
* 'v2' can be removed by mounting with 'clear_cache'
*ssd*::
*nossd*::