On Wed, May 9, 2018 at 11:39 AM, Youzhong Yang <youzhong@xxxxxxxxx> wrote: > This is what I did: > > # rbd import /var/tmp/debian93-raw.img images/debian93 > # rbd info images/debian93 > rbd image 'debian93': > size 81920 MB in 20480 objects > order 22 (4096 kB objects) > block_name_prefix: rbd_data.384b74b0dc51 > format: 2 > features: layering, exclusive-lock, object-map, fast-diff, deep-flatten > flags: > create_timestamp: Wed May 9 09:31:24 2018 > # rbd snap create images/debian93@snap > # rbd snap protect images/debian93@snap > # rbd clone images/debian93@snap vms/debian93.dsk > # rbd du vms/debian93.dsk > NAME PROVISIONED USED > debian93.dsk 81920M 336M > > --- Inside the VM --- > # df -h / > Filesystem Size Used Avail Use% Mounted on > /dev/sda1 79G 10G 66G 14% / > # fstrim -v / > /: 36.6 GiB (39311650816 bytes) trimmed > > --- then rbd du reports --- > # rbd du vms/debian93.dsk > NAME PROVISIONED USED > debian93.dsk 81920M 76028M > > === If I disable fast-diff feature from images/debian93: === > # fstrim -v / > /: 41 GiB (44059172864 bytes) trimmed > > # rbd du vms/debian93.dsk > warning: fast-diff map is not enabled for debian93.dsk. operation may be > slow. > NAME PROVISIONED USED > debian93.dsk 81920M 8612M > > === or just flatten vms/debian93.dsk without disabling fast-diff === > # rbd du vms/debian93.dsk > NAME PROVISIONED USED > debian93.dsk 81920M 11992M > > # fstrim -v / > /: 68.7 GiB (73710755840 bytes) trimmed > > # rbd du vms/debian93.dsk > NAME PROVISIONED USED > debian93.dsk 81920M 12000M > > Testing environment: > Ceph: v12.2.5 > OS: Ubuntu 18.04 > QEMU: 2.11 > libvirt: 4.0.0 > > Is this a known issue? or is the above behavior expected? What's your concern? I didn't see you state any potential problem. Are you just concerned that "fstrim" appears to increase your clone's disk usage? If that's the case, it's expected since "fast-diff" only tracks the existence of objects (not the per-object usage) and since it's a cloned image, a discard op results in the creation of a zero-byte object to "hide" the associated extent within the parent image. > Thanks, > > --Youzhong > > > _______________________________________________ > ceph-users mailing list > ceph-users@xxxxxxxxxxxxxx > http://lists.ceph.com/listinfo.cgi/ceph-users-ceph.com > -- Jason _______________________________________________ ceph-users mailing list ceph-users@xxxxxxxxxxxxxx http://lists.ceph.com/listinfo.cgi/ceph-users-ceph.com
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