Re: [ovirt-users] why replica 3

On 09/09/2015 10:14 AM, Richard Neuboeck wrote: > On 04.09.15 10:02, Simone Tiraboschi wrote: >> Is there a reason why it has to be exactly replica 3? >> >> >> To have a valid quorum having the system being able to decide witch is >> the right and safe copy avoiding an issue called split brain. >> Under certain circumstances/issues (network issue, hosts down or >> whatever could happen) the data on different replica could diverge: if >> you have two and just two different hosts that claim each other > that its >> copy is the right one there is no way to automatically take the right >> decision. Having three hosts and setting the quorum according to that >> solves/mitigates the issue. > > Thanks for the explanation. I do understand the problem but since > I'm somewhat limited in my hardware options is there a way to > override this requirement? Meaning if I change the checks for > replica 3 in the installation scripts does something else fail on > the way? > > In my case coherence checks would come from outside the storage and > vm host setup and fencing would be applied appropriately. > > I would very much appreciate it if the particulars of the storage > setup could be either selected from a list of possibilities or be > ignored and just a warning be issued that this setup is not recommended. > > Thanks! > Richard > > As a side question, in Glusterfs 3.7 there is an "AFR arbiter volume" ( http://gluster.readthedocs.org/en/release-3.7.0-1/Features/afr-arbiter-vo...) that will only contain the metadata. Will ovirt support this in 3.6?

Kind regards, Jorick Astrego Met vriendelijke groet, With kind regards, Jorick Astrego *Netbulae Virtualization Experts * ------------------------------ Tel: 053 20 30 270 info(a)netbulae.eu Staalsteden 4-3A KvK 08198180 Fax: 053 20 30 271 www.netbulae.eu 7547 TA Enschede BTW NL821234584B01 ------------------------------ _______________________________________________ Users mailing list Users(a)ovirt.org http://lists.ovirt.org/mailman/listinfo/users