Hello,
I see that free space is not released after files are removed on CephFS.
I'm using Luminous with replica=3 without any snapshots etc and with default
settings.
>From client side:
$ du -sh /mnt/logs/
4.1G /mnt/logs/
$ df -h /mnt/logs/
Filesystem Size Used Avail Use% Mounted on
h1,h2:/logs 125G 87G 39G 70% /mnt/logs
These stats are after couple of large files were removed in /mnt/logs dir, but
that only dropped Use? space a little.
Doing 'sync' command also changes nothing.
>From server side:
# ceph df
GLOBAL:
SIZE AVAIL RAW USED %RAW USED
124G 39226M 88723M 69.34
POOLS:
NAME ID USED %USED MAX AVAIL OBJECTS
cephfs_data 1 28804M 76.80 8703M 7256
cephfs_metadata 2 236M 2.65 8703M 101
Why there are such a large difference between 'du' and 'USED'?
I've found that it could be due to 'delayed delete'
http://docs.ceph.com/docs/luminous/dev/delayed-delete/
And previously it seems could be tuned by adjusting the "mds max purge files"
and "mds max purge ops"
http://lists.ceph.com/pipermail/ceph-users-ceph.com/2016-October/013679.html
But there is no more of such options in
http://docs.ceph.com/docs/luminous/cephfs/mds-config-ref/
So the question is - how to purge deleted data and reclaim free space?
Thank you.
Intermedia
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