Hi, I don't think this is the problem, because : - I use kvm RBD disk for my VM, with cache=none option - after upgrade, I didn't restart my VM to see performance drop (so rbd cache may not have changed from firefly) I put this in my config, restarted VM but nothing changed. On 11/14/2014 12:20 PM, Alexandre DERUMIER wrote: > can you try to disable rbd cache ? (which is enable by default in giant) > > [client] > rbd_cache = false > > > ----- Mail original ----- > > De: "Florent Bautista" <florent@xxxxxxxxxxx> > À: ceph-users@xxxxxxxx > Envoyé: Vendredi 14 Novembre 2014 11:54:19 > Objet: RBD read performance in Giant ? > > Hi all, > > On a testing cluster, I upgraded from Firefly to Giant. > > Without changing anything, read performance on a RBD volume (in a VM) has been divided by 4 ! > > With Firefly, in the VM (/dev/vda is a Virtio RBD device) : > > hdparm -Tt /dev/vda > > /dev/vda: > Timing cached reads: 20568 MB in 1.99 seconds = 10314.48 MB/sec > Timing buffered disk reads: 1190 MB in 3.00 seconds = 396.49 MB/sec > > > With Giant : > > hdparm -Tt /dev/vda > > /dev/vda: > Timing cached reads: 20340 MB in 1.99 seconds = 10199.48 MB/sec > Timing buffered disk reads: 318 MB in 3.00 seconds = 105.85 MB/sec > > > Write performance is the same than before, no change. > > How can we explain this ? > > Every system is running Debian Wheezy. > > Thank you a lot. > > _______________________________________________ > 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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