[Gluster-users] afr with gluster command line - possible?

[Brian Candler]

On Mon, Apr 23, 2012 at 03:46:01PM +0100, lejeczek wrote:
>    but is a true server-side replication?

No you're right, it's driven from the client side I believe. This is so that
the client can connect to either server if the other is down.

>    if I'm not mistaken, afr would take take care of it while client(fuse)
>    would suffice if only map/connect one brick
>    lets say two nodes/peers are clients at the same time, both
>    clients/bricks would only mountpoint themselves on 127.0.0.1 and
>    replication would still work, does it?

Sorry, I don't understand that question.

Using the native client, the mount is only used to make initial contact to
retrieve the volume info.  After that point, the client talks directly to
the brick(s) it needs to, as defined in the volume info.

So if you

     mount 127.0.0.1:/foo /foo

(because 127.0.0.1 happens to be one of the nodes in the cluster), and
volume /foo contains server1:/brick1 and server2:/brick2, then the client
will talk to "server1" and/or "server2" when reading and writing files.

On server1, you could put "127.0.0.1 server1" in the hosts file if you like
to force communication over that IP, but in practice using server1's public
IP is fine - it's still a loopback communication.

Indeed, if you have three nodes in your cluster, you can

    mount server3:/foo /foo

and once the volume is mounted, data transfer will only take place between
the client and server1/server2. (This is the native client remember - NFS is
different, the traffic will hit server3 and then be forwarded to server1
and/or server2 as required)

The only other "server side" replication that I know of is geo-replication.

Regards,

Brian.