2012/1/10 Michal Suba [off-list ref]:

Hello

=A0we are currently investigating performance issue on system runing =

above

btrs filesystem. Is it possible, that performance is impacted by lack=

 of

free space? Also, how to get info about real free space on btrfs volu=

me?

# btrfs-show /dev/sdb1
Label: opt =A0uuid: 28a55827-e677-47a9-98d5-d31eb3d71436
=A0 =A0Total devices 1 FS bytes used 167.83GB
=A0 =A0devid =A0 =A01 size 240.00GB used *229.25GB* path /dev/sdb1

Btrfs Btrfs v0.19

# btrfs filesystem df /opt
Data: total=3D213.23GB, used=3D165.26GB
System, DUP: total=3D8.00MB, used=3D40.00KB
System: total=3D4.00MB, used=3D0.00
Metadata, DUP: total=3D8.00GB, used=3D2.57GB

# df -h /opt
Filesystem =A0 =A0 =A0 =A0 =A0 =A0Size =A0Used Avail Use% Mounted on
/dev/sdb1 =A0 =A0 =A0 =A0 =A0 =A0 240G =A0171G =A0 59G =A075% /opt

How come that there is difference detween btrfs-show and df .. 40GB I=

s the

space really usead or can I claim it back? (there are no snapshots)

# btrfs subvolume list /opt
#

The btrfs-show command is being deprecated.  It's output can be easy
to misunderstand, but it probably won't be corrected since it's going
away at some point.

Basically, what this is telling you is that 229.25GB is "committed"
(213.23GB Data + 2 x8.00GB Metadata (because it's duplicated) + 2 x
8.00MB System.

However, all the "committed" space is not being used (which is clearer
in the 'btrfs filesystem df' command).
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