[ovirt-users] Q: oVirt and NFS / GlusterFS High-Availability File Sync Algorithm

[Andrei V]

Hi,

I would like to ask how (almost) high-availability file sync algorithm
works with very simple setup:
2-node (1 main and another backup) + engine on separate PC;
each node - Xeon server with RAID L5 for data domain.

With GlusterFS copy of each VM disk(s) is being stored on each node data
domain and kept up-to-date by GlusterFS sync process automatically.
How this works if data domains are on NFS data domains / volumes ?

My current setup is really simple, and don't need to be complicated any
further. 1st (main) node runs all the time, 2nd (backup) activated only
if 1st suffer for example a hardware failure. Anyway, both data domains
linked to 2 nodes must be kept fully synced.
Right now I finished setup only of 1st node (with CentOS 7, not oVirt
node appliance which wipes out all custom software changes upon
upgrade). Node data domain runs on GlusterFS.
Upon finishing setup of 2nd node (with GlusterFS) they will be joined as
Replica 2, and all VMs will be marked as highly available.

Since during normal operation all VM disks are being active only on one
node, and synced to 2nd (backup), I hope to avoid GlusterFS split brain
issue.

Please correct me if I'm wrong here. Quite possible I don't entirely
understand all underlying algorithms.

Thanks in advance
Andrei