[Gluster-users] Multiple Networks

[Prof. Dr. Michael Schefczyk]

Dear All,

having read the November discussion on multiple networks, I am seeking advice regarding how to deal with the following situation:

I run a two small (-> for private purposes, reasonable servers, but not high-performance computing) Centos 7 KVM server clusters in two different cities. Each of the two clusters has a storage network available only among the cluster members. Both clusters are connected via a fast VPN. I did manage to set up Gluster as shared storage among the servers within each cluster. The servers both (a) run the bricks and (b) are clients. They do interconnect via the storage network (two 1 GB NICs bonded in one city and a 10 GB network in the other city).

I start to use Kolab as an email server. Kolab's IMAP store is straightforward and fairly low traffic. For high availability purposes, I have redundant email servers in both locations. To share the IMAP store, I would like to use one Gluster volume overlapping both locations (https://docs.kolab.org/howtos/deploy-kolab-with-glusterfs-for-imap.html). The VPN is not the bottleneck. I would like to avoid Gluster Geo-replication, as this is not a master-slave-situation for disaster recovery, but rather bidirectional and synchronous for high availability.

Then the problem kicks in: All servers can ping each other via the general LAN. However, the storage network is available strictly only within each cluster locally in a given city. The gluster peering within each cluster uses the storage network IPs. I did not find a reasonable way to peer across cities. Of course, I did try to use the host file in the way that I use hostnames instead of IPs for the peering and resolve the hostnames to the storage network where available and to the general LAN elsewhere. However, Gluster still stores resolved IPs even when using hostnames in the gluster peer probe command.

Can someone please point me in the right direction? It may be possible to use static routing to enforce the use of the storage network where available. However, I would like to avoid that for multiple reasons (as static routes are intended for multiple subnets while peering would imply that I collapse everything into general LAN addresses and as one storage network includes a NAS for which I am uncertain about its static routing capabilities).

Regards,

Michael
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