[OpenAFS] read-write replication in other fs's

[Sven]

Nathan Neulinger nneul@umr.edu wrote:
> From: Nathan Neulinger <nneul@umr.edu>
> To: openafs-info@openafs.org
> Organization: University of Missouri - Rolla
> Date: 02 Jun 2003 17:08:46 -0500
> Subject: [OpenAFS] read-write replication in other fs's
>
> Obviously AFS doesn't have read write replication... I know coda and
> intermezzo do something, but theyy are so alpha as to be pointless in a
> production context.
>
> Someone recently suggested (at a training session) that microsoft's DFS
> has fully redundant RW replication. Can anyone here corroborate or
> refute that? More importantly - if it does, is the situation something
> like:

> "Sure, it has RW replication in the same way that exchange has
> active-active clustering. You're insane to use it cause it causes more
> problems than it helps."

We have been using microsoft's DFS in a clustered web environment with quite
some success. It is a truly redundant system whereby writes to any node are
immediately replicated to the other nodes in the cluster. The caveat is that
the machines must be in sync time-wise (which is required by the Kerberos
and Active-Directory Replication systems anyway). The only issue we have had
is when power failures and backup power issues caused both replicated nodes
to go down and get out of sync timewise. The fix was to point traffic to one
node and rebuild the dfs which took about 6 or so hours.

I have been trying to eliminate Microsoft servers from our environment for
some time, but the DFS scenario has been difficult to find a workable
replacement for. I had originally looked to AFS for this exact reason; for
static websites that only change periodically where ftp traffic could be
directed to the r/w volume, this would work. For busy servers with multiple
vhosts and frequent webpage updates, the AFS solution starts to lose
horsepower though.

If anyone knows of a viable replacement for the MS DFS/replication
situation, I would be eager to hear about it.

Sven Willenberger
Systems Administration
Delmarva Online, Inc.