[ovirt-users] oVirt/gluster storage questions for 2-3 node datacenter

[Vijay Bellur]

On 08/29/2014 07:34 PM, David King wrote:
> Paul,
>
> Thanks for the response.
>
> You mention that the issue is orphaned files during updates when one
> node is down.  However I am less concerned about adding and removing
> files because the file server will be predominately VM disks so the file
> structure is fairly static.  Those VM files will be quite active however
> - will gluster be able to keep track of partial updates to a large file
> when one out of two bricks are down?
>

Yes, gluster only updates regions of the file that need to be 
synchronized during self-healing. More details on this synchronization 
can be found in the self-healing section of afr's design document [1].

> Right now I am leaning towards using SSD for "host local" disk - single
> brick gluster volumes intended for VMs which are node specific and then
> 3 way replicas for the higher availability zones which tend to be more
> read oriented.   I presume that read-only access only needs to get data
> from one of the 3 replicas so that should be reasonably performant.

Yes, read operations are directed to only one of the replicas.

Regards,
Vijay

[1] https://github.com/gluster/glusterfs/blob/master/doc/features/afr-v1.md