I might have missed something in the question. Fstrim does not free up space at the user level that you see with a normal df.
It is meant to let the block device know about all of the space unused by the file system. Regards, Ric On Jan 29, 2018 11:56 AM, "Wido den Hollander" <[email protected]> wrote: > > > On 01/29/2018 12:29 PM, Nathan Harper wrote: > >> Hi, >> >> I don't know if this is strictly a Ceph issue, but hoping someone will be >> able to shed some light. We have an Openstack environment (Ocata) backed >> onto a Jewel cluster. >> >> We recently ran into some issues with full OSDs but couldn't work out >> what was filling up the pools. >> >> It appears that fstrim isn't actually working (or being ignored) within >> the instances: >> >> [centos@with ~]$ df -h >> Filesystem Size Used Avail Use% Mounted on >> /dev/sda1 8.0G 1.2G 6.9G 14% / >> >> plenty of unused space that can be reclaimed: >> >> running fstrim: >> [centos@with ~]$ sudo fstrim -a -v >> /: 6.9 GiB (7416942592 bytes) trimmed >> >> however, running the command again: >> >> [centos@with ~]$ sudo fstrim -a -v >> /: 6.9 GiB (7416942592 bytes) trimmed >> >> > It depends on the FS you use inside the VM. > > iirc XFS will always tell you the total free space of the FS being trimmed > and ext4 only the actual bytes which are trimmed. > > The discard option was enabled following: >> https://ceph.com/geen-categorie/openstack-and-ceph-rbd-discard/ >> >> Have I missed anything at the Ceph layer to enable this? Is there >> anything I can do to see if the request is making it's way through to the >> Ceph layer? >> >> > Try using 'rbd du' and see if it makes a difference. > > You also want to check if the XML definition of libvirt has unmap enabled > although I expect it does since you don't see any errors. > > Wido > > >> >> -- >> *NathanHarper* // IT Systems Lead >> >> *e: *[email protected] <mailto:[email protected]> >> *t*: 0117 906 1104 *m*: 0787 551 0891 *w: *www.cfms.org.uk < >> http://www.cfms.org.uk/> >> CFMS Services Ltd // Bristol & Bath Science Park // Dirac Crescent // >> Emersons Green // Bristol // BS16 7FR >> CFMS Services Ltd is registered in England and Wales No 05742022 - a >> subsidiary of CFMS Ltd >> CFMS Services Ltd registered office // 43 Queens Square // Bristol // BS1 >> 4QP >> >> >> _______________________________________________ >> ceph-users mailing list >> [email protected] >> http://lists.ceph.com/listinfo.cgi/ceph-users-ceph.com >> >> _______________________________________________ > ceph-users mailing list > [email protected] > http://lists.ceph.com/listinfo.cgi/ceph-users-ceph.com >
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