Hi Alexandre, Thanks for the note. I was not clear enough. The fstrim I was running was only on the krbd mountpoints. The backend OSDs only have standard hard disks, not SSDs, so they don't need to be trimmed. Instead I was reclaiming free space as reported by Ceph. Running fstrim on the rbd mountpoints this caused the OSDs to become very busy, affecting all rbds, not just those being trimmed. I was hoping someone had an idea of how to make the OSDs not become busy while running fstrim on the rbd mountpoints. E.g. if Ceph made a distinction between trim operations on RBDs and other types, it could give those operations lower priority. Thanks again! Chad. On Monday, August 24, 2015 18:26:30 you wrote: > Hi, > > I'm not sure for krbd, but with librbd, using trim/discard on the client, > > don't do trim/discard on the osd physical disk. > > It's simply write zeroes in the rbd image. > > zeores write can be skipped since this commit (librbd related) > https://github.com/xiaoxichen/ceph/commit/e7812b8416012141cf8faef577e7b27e1b > 29d5e3 +OPTION(rbd_skip_partial_discard, OPT_BOOL, false) > > > Then you can still manage fstrim manually on the osd servers > > ----- Mail original ----- > De: "Chad William Seys" <cwseys@xxxxxxxxxxxxxxxx> > À: "ceph-users" <ceph-users@xxxxxxxx> > Envoyé: Samedi 22 Août 2015 04:26:38 > Objet: TRIM / DISCARD run at low priority by the OSDs? > > Hi All, > > Is it possible to give TRIM / DISCARD initiated by krbd low priority on the > OSDs? > > I know it is possible to run fstrim at Idle priority on the rbd mount point, > e.g. ionice -c Idle fstrim -v $MOUNT . > > But this Idle priority (it appears) only is within the context of the node > executing fstrim . If the node executing fstrim is Idle then the OSDs are > very busy and performance suffers. > > Is it possible to tell the OSD daemons (or whatever) to perform the TRIMs at > low priority also? > > Thanks! > Chad. > _______________________________________________ > ceph-users mailing list > ceph-users@xxxxxxxxxxxxxx > http://lists.ceph.com/listinfo.cgi/ceph-users-ceph.com _______________________________________________ ceph-users mailing list ceph-users@xxxxxxxxxxxxxx http://lists.ceph.com/listinfo.cgi/ceph-users-ceph.com
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