I need some clarification on how geo-replication (gluster => 3.5) operates, as I'm not fully understanding how the new and improved version works from the docs. Let's assume the following scenario, three servers setup in a geo-rep cluster all separated by a WAN: <server a> -- WAN -- <server b> -- WAN -- <server c> Does this scenario allow for a client with the a volume mounted to write to any of the servers directly and the write then gets replicated from that server to the other servers? For example, a client has the volume mounted (via FUSE) on server C and writes a file, does that file get written to server C directly and then the file replicates (asynchronously) to server A and server B ? Or is it that the writes only occur on the "master" of that geo-rep volume? I'm trying to understand if the replication for geo-rep occurs in a master-master setup or if it's still master-slave ? What was the big change for geo-rep in 3.5 ? If it's not master-master, how does one get master-master replication working over a WAN? Thanks ... -------------- next part -------------- An HTML attachment was scrubbed... URL: <http://www.gluster.org/pipermail/gluster-users/attachments/20150609/c2edc73f/attachment.html>
M S Vishwanath Bhat
2015-Jun-10 11:37 UTC
[Gluster-users] geo-replication vs replicated volumes
On 10 June 2015 at 12:24, Gabriel Kuri <gkuri at ieee.org> wrote:> I need some clarification on how geo-replication (gluster => 3.5) > operates, as I'm not fully understanding how the new and improved version > works from the docs. > > Let's assume the following scenario, three servers setup in a geo-rep > cluster all separated by a WAN: > > <server a> -- WAN -- <server b> -- WAN -- <server c> > > Does this scenario allow for a client with the a volume mounted to write > to any of the servers directly and the write then gets replicated from that > server to the other servers? For example, a client has the volume mounted > (via FUSE) on server C and writes a file, does that file get written to > server C directly and then the file replicates (asynchronously) to server A > and server B ? Or is it that the writes only occur on the "master" of that > geo-rep volume? I'm trying to understand if the replication for geo-rep > occurs in a master-master setup or if it's still master-slave ? What was > the big change for geo-rep in 3.5 ? >glusterfs doesn't support master-master yet. In your case, one of the servers (A or B or C) should be a master and your client should write to only that volume. Other two volumes should be read-only till volume in server-A fails for some reason. The big change in glusterfs-3.5 was the design of the geo-replication. Earlier one single node in master volume was responsible for syncing data to slave (which has lots of performance problems). So from > glusterfs-3.5, the responsibility of syncing is shared across servers of volume in master.> > If it's not master-master, how does one get master-master replication > working over a WAN? >AFAIK, there is no work around as of now, at least I am not aware of it Best Regards, Vishwanath> Thanks ... > > > _______________________________________________ > Gluster-users mailing list > Gluster-users at gluster.org > http://www.gluster.org/mailman/listinfo/gluster-users >-------------- next part -------------- An HTML attachment was scrubbed... URL: <http://www.gluster.org/pipermail/gluster-users/attachments/20150610/f73f2fb1/attachment.html>