[ovirt-users] oVirt & gluster - which copy is written to?
sabose at redhat.com
Tue May 17 07:05:05 UTC 2016
On 05/12/2016 05:35 AM, Bill Bill wrote:
> Let’s say I have a 5 node converged cluster of oVirt & glusterFS with
> a replica count of “3”.
> Host1 - replica
> Host2 - replica
> Host3 - replica
> If I spin a VM up on Host1 – does the first replica get created local
> to that server?
> In the event I move the VM to another host, does the replica of the
> disk follow the VM so essentially it’s writing to a local copy first
> or does it “always” write across the network.
Any writes are written to all 3 hosts that form the replica 3 gluster
volume. Replica 3 - indicates that there is a 3-way copy of data, and
the same data resides on Host1, Host2 and Host3.
Reads however are from local host. So for a VM running on Host1, it will
access the data (i.e. read) from the brick on Host1.
> For example, with VMware, the disk will follow the VM to the
> hypervisor you move it to so that the writes are essentially “local”.
> I have not been able to find anything on the internet or in the
> documentation that specifies how this process works. Ideally, you
> wouldn’t want a VM residing on Host1 that accesses its disk on Host3.
> Multiple that by hundreds of VM’s and it would create a ton of
> unnecessary network congestion.
> Users mailing list
> Users at ovirt.org
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