Highly available and scalable Cyrus configurations

[Ben Carter]

We currently have a single IMAP server and we are considering two 
Solaris 8/9 HA Cyrus configurations:

#1. IMAP Aggregator (murder)
#2. Cyrus on a Veritas cluster (common file system with parallel service 
groups)

After looking at the  murder design,  it seems to  me that it's a lot 
more complicated than having a Veritas cluster and simply running imapd 
and an MTA on each cluster member, because with the murder 
configuration, you probably have to end up with a load-balancing switch 
in front of murder front-end machines which in turn are in front of the 
backend mailstore machines.  mupdate has to be run and mail delivery has 
to be directed to the correct machine, etc.  Moreover, with the murder 
design, backend machines would have to be clustered anyway (2-node 
clusters probably) to eliminate the back-end machines as SPOFs.

With a cluster configuration, all machines would run sendmail and 
master/imapd and offer exactly the same service.  A load-balancing 
switch is in front of the cluster and any cluster machine can go down 
without losing any service.  I can't see any functionality that would be 
lost but I'm pretty sure that the cluster solution will be more 
expensive even though the expense of buying murder front-end machines 
would be eliminated.

So, my first question is: has anyone implemented a Veritas-based Cyrus 
service?

And my second question is: is there something I'm missing with regard to 
the Veritas cluster being a much simpler configuration to troubleshoot 
and operate and a much stronger configuration in terms of availability?

TIA for all input.

Ben Carter
University of Pittsburgh/CSSD
bhc at pitt.edu
412-624-6470