[Gluster-devel] New wiki page for 2 server afr, client side afr

[Brandon Lamb]

On Fri, May 2, 2008 at 3:04 AM, Daniel Maher <dma+gluster at witbe.net> wrote:
>
> On Thu, 1 May 2008 14:47:39 -0700 "Brandon Lamb"
> <brandonlamb at gmail.com> wrote:
>
> > http://www.gluster.org/docs/index.php/Setting_up_AFR_on_two_servers_with_client_side_replication
> >
> > Look over and make sure it is kosher?
> >
> > I added a section at the bottom for "gotchas", can you take a quick
> > look to make sure they are accurate statements.
>
> From the wiki page :
>
> "As you can see the cluster came back. During the time that server2 is
> down, the file system does not seem to be available. This does not bode
> well when we need or want to be able to down one of the data servers
> for whatever reason. Hence client side AFR is recommended over server
> side."
>
> IMHO, the conclusion that you've drawn here is somewhat misleading.  By
> using RRDNS to allocate a single hostname to all (both) nodes in the
> AFR server cluster, the problem you're describing can be avoided
> entirely.
>
> While i realise that your wiki articles are meant to be as simple as
> possible (and, therefore, a discussion of RRDNS is out of scope), it
> would be remiss to not (at least) link to further information on the
> subject.
>
>
> --
> Daniel Maher <dma AT witbe.net>

Actually from what I am seeing in my testing that would not be true.
Also with RRDNS you would have dns ttl issues where you could be
directed to a server that was down? I use LVS for all my major
services so dont run into that problem.

However, that aside, rrdns would not solve this problem. client1 was
still connected to server1 which was up and running, but it could not
read or write to existing files, although i was able to create a NEW
file for some reason while server2 was down. So using rrdns to make
the clients connect to a working server *so far from what I am seeing*
would not solve anything. Yes it would get a client to connect to
server1 which was up, but the cluster still doesnt work.

I will be more doing more extensive testing today per request by
Krishna with debugging on and updating wiki as needed. More to come!
Hopefully I just have something goofy going on.

NOTE TO KRISHNA:
Could this have ANYTHING to do with the possiblity that I am using two
network interfaces? Could it for *some* reason be getting confused
that server1 and server2 are talking on 192.168.0 and my clients are
talking to the servers on 208.200.248?

I will test this out as well