Did you try balance ? (also there is a balance option
to pick the least utilized metadata chunks).
in long run when you have the understanding of your
files and sizes tuning using mount option metadata_ratio
might help.
but not sure how the metadata expanded to 84.38G
was there any major delete operation on the filesystem?
thanks, Anand
On 13/06/12 01:38, Calvin Walton wrote:
On Sat, 2012-06-09 at 01:38 +0600, Roman Mamedov wrote:
Hello,
Before the upgrade (on 3.2.18):
Metadata, DUP: total=9.38GB, used=5.94GB
After the FS has been mounted once with 3.4.1:
Data: total=3.44TB, used=2.67TB
System, DUP: total=8.00MB, used=412.00KB
System: total=4.00MB, used=0.00
Metadata, DUP: total=84.38GB, used=5.94GB
Where did my 75 GB of free space just went?
Btrfs tries to keep a certain ratio of allocated data space to allocated
metadata space at all times, in order to ensure that there is always
some free metadata space available. In 3.3 (I believe, but haven't
actually checked...) this ratio was increased, since people were still
complaining about btrfs reporting out of space errors too soon.
On a filesystem containing (a relatively small number of) large files,
it probably over-allocates the metadata space, which is what you're
seeing. I'm not sure if the ratio is tunable.
But better to have a bit of unused metadata space than to get 'out of
space' errors once you've filled your disk and you're trying to delete
some files!
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