Christian Balzer,thanks for your reply. you say,kernel upgrade will interrupt service.but AFAIK,umount rbd and strim it on another machine will interrupt service too. In my environment,all krbd are online business,service interruption is now allow. 2016-05-21 11:58 GMT+08:00 Christian Balzer <chibi@xxxxxxx>: > On Fri, 20 May 2016 17:00:03 +0800 lin zhou wrote: > >> Hi,cephers >> we only using krbd in ceph.and it works well near two yeas.but now I >> face a size problem. >> >> I have 7 nodes with 10 3T osd each.we using ceph 0.67.9 in >> ubuntu12.04.I know it is too old,but update is beyond my control. >> >> and now we use 80% size,so we start to delete historic unneeded >> data,but free size do not increase. >> >> and then I found total assigned size of rbds are much bigger than >> ceph size,so it means if we do not do something,it will reach the >> limit. >> >> but the true data in the user side,we only use 40%. >> >> I read the blog of Sebastien and some maillist.I know the command of >> fstrim in kernel 3.18 can deal with it. and is it risky that update >> kernel to 3.18 in ubuntu12.04? >> >> I try to add discard option in mount command,but it do not work. >> >> so what way do you recommend to free krbd size in ceph 0.67.9 in >> ubuntu12.04 >> > > If you're considering a kernel upgrade (and thus a service interruption), > another option would be to unmount that image on your old machine, mount > it on a newer machine and/or with librbd and fuse and then run fstrim. > > However trim is a pretty costly activity in Ceph, so it may > a) impact your cluster performance and > b) take a while, depending on how much data we're talking about. > > Lastly, while having a sparse storage serice like Ceph is very nice I > always try to have enough actual space available to handle all > commitments. > > Christian > -- > Christian Balzer Network/Systems Engineer > chibi@xxxxxxx Global OnLine Japan/Rakuten Communications > http://www.gol.com/ _______________________________________________ ceph-users mailing list ceph-users@xxxxxxxxxxxxxx http://lists.ceph.com/listinfo.cgi/ceph-users-ceph.com
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