Hi Fernando / Christian, Many thanks for getting back to me. Slow writes are acceptable; most of our VM's are small web servers with low traffic. My aim is to have a fully self-contained two server KVM cluster with live migration, no external storage and the ability to reboot either node with zero VM downtime. We seem to be "almost there", bar a hiccup when the self-heal is in progress and some minor grumbles from sanlock (which might be fixed by the new sanlock in RHEL 6.3) Incidentally, the logs shows a "diff" self heal on a node reboot: [2012-07-09 16:04:06.743512] I [afr-self-heal-algorithm.c:122:sh_loop_driver_done] 0-gluster-rep-replicate-0: diff self-heal on /box1-clone2.img: completed. (16 blocks of 16974 were different (0.09%)) So, does this log show "Granular locking" occurring, or does it just happen transparently when a file exceeds a certain size? many thanks Jake On 07/09/2012 04:01 PM, Fernando Frediani (Qube) wrote: > Jake, > > I haven?t had a chanced to test with my KVM cluster yet but it should be > a default things from 3.3. > > Just be in mind that running Virtual Machines is NOT a supported things > for Redhat Storage server according to Redhat Sales people. They said > towards the end of the year. As you might have observed performance > specially for write isn?t any near fantastic. > > > Fernando > > *From:*gluster-users-bounces at gluster.org > [mailto:gluster-users-bounces at gluster.org] *On Behalf Of *Christian Wittwer > *Sent:* 09 July 2012 15:51 > *To:* Jake Grimmett > *Cc:* gluster-users at gluster.org > *Subject:* Re: "Granular locking" - does this need to be > enabled in 3.3.0 ? > > Hi Jake > > I can confirm exact the same behaviour with gluster 3.3.0 on Ubuntu > 12.04. During the self-heal process the VM gets 100% I/O wait and is locked. > > After the self-heal the root filesystem was read-only which forced me to > do a reboot and fsck. > > Cheers, > > Christian > > 2012/7/9 Jake Grimmett <jog at mrc-lmb.cam.ac.uk > <mailto:jog at mrc-lmb.cam.ac.uk>> > > Dear All, > > I have a pair of Scientific Linux 6.2 servers, acting as KVM > virtualisation hosts for ~30 VM's. The VM images are stored in a > replicated gluster volume shared between the two servers. Live migration > works fine, and the sanlock prevents me from (stupidly) starting the > same VM on both machines. Each server has 10GB ethernet and a 10 disk > RAID5 array. > > If I migrate all the VM's to server #1 and shutdown server #2, all works > perfectly with no interruption. When I restart server #2, the VM's > freeze while the self-heal process is running - and this healing can > take a long time. > > I'm not sure if "Granular Locking" is on. It's listed as a "technology > preview" in the Redhat Storage server 2 notes - do I need to do anything > to enable it? > > i.e. set "cluster.data-self-heal-algorithm" to diff ? > or edit "cluster.self-heal-window-size" ? > > any tips from other people doing similar much appreciated! > > Many thanks, > > Jake > > jog <---at---> mrc-lmb.cam.ac.uk <http://mrc-lmb.cam.ac.uk> > _______________________________________________ > Gluster-users mailing list > Gluster-users at gluster.org <mailto:Gluster-users at gluster.org> > http://gluster.org/cgi-bin/mailman/listinfo/gluster-users > -- Dr Jake Grimmett Head Of Scientific Computing MRC Laboratory of Molecular Biology Hills Road, Cambridge, CB2 0QH, UK. Phone 01223 402219 Mobile 0776 9886539
