On 23.07.2018 22:18, Sean Bolding wrote:
I have XenServers that connect via iSCSI to Ceph gateway servers that
use lrbd and targetcli. On my ceph cluster the RBD images I create are
used as storage repositories in Xenserver for the virtual machine vdisks.
Whenever I delete a virtual machine, XenServer shows that the
repository size has decreased. This also happens when I mount a
virtual drive in Xenserver as a virtual drive in a Windows guest. If I
delete a large file, such as an exported VM, it shows as deleted and
space available. However; when check in Ceph using ceph –s or ceph df
it still shows the space being used.
I checked everywhere and it seems there was a reference to it here
https://github.com/ceph/ceph/pull/14727 but not sure if a way to trim
or discard freed blocks was ever implemented.
The only way I have found is to play musical chairs and move the VMs
to different repositories and then completely remove the old RBD
images in ceph. This is not exactly easy to do.
Is there a way to reclaim free space on RBD images that use
Bluestore????? What commands do I use and where do I use this from? If
such command exist do I run them on the ceph cluster or do I run them
from XenServer? Please help.
Sean
I am not familiar with Xen, but it does sounds like you have a rbd
mounted with a filesystem on the xen server.
in that case it is the same as for other filesystems. Deleted files are
just deleted in the file allocation table, and the RBD space is
"reclaimed" when the filesystem zeroes out the now unused blocks.
in many filesystems you would run the fstrim command to overwrite free'd
blocks with zeroes, optionally mount the fs with the the discard option.
in xenserver >6.5 this should be a button in xencenter to reclaim freed
space.
kind regards
Ronny Aasen
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