Hi, in a 2 node cluster you can set the path to localhost:volume. If one host goes down and SPM role switches to the remaining running host, your master domain is still accessible and so your VMs stay up and running.
Regards, Alex -----Original message----- > From:[email protected] <[email protected]> > Sent: Friday 20th December 2013 15:10 > To: Andrew Lau <[email protected]> > Cc: users <[email protected]> > Subject: Re: [Users] GlusterFS Distributed Replicate > > Hi, > > There are some things I don't understand. First of all, why do we need > keepalived ? I thought that it would be transparent at this layer and > that glusterfs would manage all the replication thing by itself. Is that > because I've POSIXFS instead of GlusterFS or is it totally unrelated ? > > Secondly, about the split-brain, when you says that I can read but not > write, does that mean I can't write data on the VM storage space or > can't I create VM ? If I can't write data, what would be the workaround > ? Am I force to have 3 (or 4, I guess, as I want to get replication) > nodes ? > > To conclude : can I get real HA (except engine) with Ovirt / Glusterfs > with 2 nodes ? > > Thank you very much, > Regards, > Grégoire Leroy > > > Le 2013-12-19 23:03, Andrew Lau a écrit : > > Hi, > > > > What I learned in the way glusterfs works is you specify the host > > only to grab the initial volume information, then it'll go directly to > > the other hosts to connect to the datastore - this avoids the > > bottleneck issue that NFS has. > > > > Knowing this, the work around I used was to setup keepalived on the > > gluster hosts (make sure you set it up on an interface other than your > > ovirtmgmt or you'll clash with the live migration components). So now > > if one of my hosts drop from the cluster, the storage access is not > > lost. I haven't fully tested the whole infrastructure yet but my only > > fear is they may drop into "PAUSE" mode during the keepalived > > transition period. > > > > Also - you may need to change your glusterfs ports so they don't > > interfere with vdsm. My post here was a little outdated but it still > > has my findings on keepalived > > etc. http://www.andrewklau.com/returning-to-glusterized-ovirt-3-3/ > > [2] > > > > The other thing to note, is you've only got two gluster hosts. I > > believe by default now ovirt sets the quorum setting which enforces > > that there must be atleast 2 nodes alive in your configuration. This > > means when there is only 1 gluster server up, you'll be able to read > > but not write this is to avoid split-brain. > > > > Thanks, > > Andrew > > > > On Thu, Dec 19, 2013 at 5:12 AM, <[email protected]> wrote: > > > >> Hello, > >> > >> As I said in a previous email, I have this configuration with Ovirt > >> 3.3 : > >> 1 Ovirt Engine > >> 2 Hosts Centos 6.5 > >> > >> I successfully setup GlusterFS. I created a distributed replicate > >> volume with 2 bricks : host1:/gluster and host2:/gluster. > >> > >> Then, I created a storage storage_gluster POSIXFS with the option > >> glusterfs and I gave the path "host1:/gluster". > >> > >> First, I'm rather surprised I have to specify an host for the > >> storage as I wish to have a distribute replicated storage. I > >> expected to specify both hosts. > >> > >> Then I create a VM on this storage. The expected behaviour if I > >> shutdown host1 should be that my VM keeps running on the second > >> brick. Yet, not only I lose my VM but host2 is in a non operationnal > >> status because one of its data storage is not reachable. > >> > >> Did I miss something in the configuration ? How could I get the > >> wanted behaviour ? > >> > >> Thanks a lot, > >> Regards, > >> Grégoire Leroy > >> _______________________________________________ > >> Users mailing list > >> [email protected] > >> http://lists.ovirt.org/mailman/listinfo/users [1] > > > > > > > > Links: > > ------ > > [1] http://lists.ovirt.org/mailman/listinfo/users > > [2] http://www.andrewklau.com/returning-to-glusterized-ovirt-3-3/ > _______________________________________________ > Users mailing list > [email protected] > http://lists.ovirt.org/mailman/listinfo/users > _______________________________________________ Users mailing list [email protected] http://lists.ovirt.org/mailman/listinfo/users
