>>Unfortunately I didn't, do you think hdparm could wrong results ? I really don't known how hdparm is doing his bench (block size ? number of thread ?).
BTW, do you have also upgraded librbd on your kvm node ? (and restarted the vm) ----- Mail original ----- De: "Florent Bautista" <[email protected]> À: "Alexandre DERUMIER" <[email protected]> Cc: [email protected] Envoyé: Vendredi 14 Novembre 2014 12:40:24 Objet: Re: [ceph-users] RBD read performance in Giant ? Unfortunately I didn't, do you think hdparm could wrong results ? On 11/14/2014 12:37 PM, Alexandre DERUMIER wrote: > Do you have tried to bench with something like fio ? > > > ----- Mail original ----- > > De: "Florent Bautista" <[email protected]> > À: "Alexandre DERUMIER" <[email protected]> > Cc: [email protected] > Envoyé: Vendredi 14 Novembre 2014 12:30:21 > Objet: Re: [ceph-users] RBD read performance in Giant ? > > 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" <[email protected]> >> À: [email protected] >> Envoyé: Vendredi 14 Novembre 2014 11:54:19 >> Objet: [ceph-users] 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 >> [email protected] >> http://lists.ceph.com/listinfo.cgi/ceph-users-ceph.com _______________________________________________ ceph-users mailing list [email protected] http://lists.ceph.com/listinfo.cgi/ceph-users-ceph.com
