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authorDavid Sterba <dsterba@suse.com>2016-07-28 13:14:08 +0200
committerDavid Sterba <dsterba@suse.com>2016-07-28 14:08:30 +0200
commit2f732723d6c1e3b6e9205e96da4c600ee72de875 (patch)
tree5eafd136b2353a773bbd08b63af8ac2c49752ae9 /Documentation
parent2542112e0ce4558ea7cf2d27104469c5e3709f4e (diff)
btrfs-progs: fi defrag: change default extent target size to 32 MiB
The kernel default is too low, 32 MiB is recommended and should give better results. Signed-off-by: David Sterba <dsterba@suse.com>
Diffstat (limited to 'Documentation')
-rw-r--r--Documentation/btrfs-filesystem.asciidoc16
1 files changed, 12 insertions, 4 deletions
diff --git a/Documentation/btrfs-filesystem.asciidoc b/Documentation/btrfs-filesystem.asciidoc
index 8fb15eac..9782af9b 100644
--- a/Documentation/btrfs-filesystem.asciidoc
+++ b/Documentation/btrfs-filesystem.asciidoc
@@ -117,15 +117,23 @@ compression. See also section 'EXAMPLES'.
-r::::
defragment files recursively in given directories
-f::::
-flush data for each file before going to the next file. This will limit the amount
-of dirty data to current file, otherwise the amount cumulates from several files
-and may increase system load.
+flush data for each file before going to the next file.
++
+This will limit the amount of dirty data to current file, otherwise the amount
+cumulates from several files and will increase system load. This can also lead
+to ENOSPC if there's too much dirty data to write and it's not possible to make
+the reservations for the new data (ie. how the COW design works).
++
-s <start>[kKmMgGtTpPeE]::::
defragmentation will start from the given offset, default is beginning of a file
-l <len>[kKmMgGtTpPeE]::::
defragment only up to 'len' bytes, default is the file size
-t <size>[kKmMgGtTpPeE]::::
-target extent size, do not touch extents bigger than 'size'
+target extent size, do not touch extents bigger than 'size', default: 32M
++
+The value is only advisory and the final size of the extents may differ,
+depending on the state of the free space and fragmentation or other internal
+logic. Reasonable values are from tens to hundreds of megabytes.
*du* [options] <path> [<path>..]::
Calculate disk usage of the target files using FIEMAP. For individual