RepoMirrors/btrfs-progs
1
0
Fork 0
mirror of https://github.com/kdave/btrfs-progs synced 2025-02-11 07:07:11 +00:00
Code Issues Packages Projects Releases Wiki Activity

btrfs-progs: document snapshot unaware defrag

Browse Source 
In btrfs-filesystem(8), improved the documentation of snapshot unaware
defragmentation and included the exact kernel version numbers being affected as
well as the possible effects.
No longer use the word "unlink" which is easily understood as "deleting a file".
Moved the warning more to the beginning of "defragment" subcommand's
documentation where it's more visible to readers.

Added the same warning to the "autodefrag" option of btrfs-mount(5).

Signed-off-by: Christoph Anton Mitterer <mail@christoph.anton.mitterer.name>
This commit is contained in:
Christoph Anton Mitterer 2015-12-27 03:41:28 +01:00 committed by David Sterba
parent 894c346714
commit d0ba996f5f
2 changed files with 14 additions and 4 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

11
Documentation/btrfs-filesystem.asciidoc
View File

@ -55,6 +55,13 @@ if the free space is too fragmented.
Use 0 to take the kernel default, which is 256kB but may change in the future.
You can also turn on compression in defragment operations.
+
WARNING: Defragmenting with Linux kernel versions < 3.9 or ≥ 3.14-rc2 as well as
with Linux stable kernel versions ≥ 3.10.31, ≥ 3.12.12 or ≥ 3.13.4 will break up
the ref-links of CoW data (for example files copied with `cp --reflink`,
snapshots or de-duplicated data).
This may cause considerable increase of space usage depending on the broken up
ref-links.
+
`Options`
+
-v::::
@ -79,10 +86,6 @@ target extent size, do not touch extents bigger than <size>
For <start>, <len>, <size> it is possible to append
units designator: \'K', \'M', \'G', \'T', \'P', or \'E', which represent
KiB, MiB, GiB, TiB, PiB, or EiB, respectively. Case does not matter.
+
WARNING: defragmenting with kernels up to 2.6.37 will unlink COW-ed copies of data,
don't use it if you use snapshots, have de-duplicated your data or made
copies with `cp --reflink`.
*label* [<dev>|<mountpoint>] [<newlabel>]::
Show or update the label of a filesystem.

7
Documentation/btrfs-mount.asciidoc
View File

@ -26,6 +26,13 @@ MOUNT OPTIONS
Auto defragmentation detects small random writes into files and queue
them up for the defrag process. Works best for small files;
Not well suited for large database workloads.
+
WARNING: Defragmenting with Linux kernel versions < 3.9 or ≥ 3.14-rc2 as
well as with Linux stable kernel versions ≥ 3.10.31, ≥ 3.12.12 or
≥ 3.13.4 will break up the ref-links of CoW data (for example files
copied with `cp --reflink`, snapshots or de-duplicated data).
This may cause considerable increase of space usage depending on the
broken up ref-links.
*check_int*::
*check_int_data*::