High availability email server...

[Rich Graves]

Fabio Corazza wrote:
> Rich Graves wrote:
>> Clustered filesystems don't make any sense for Cyrus, since the
>> application itself doesn't allow simultaneous read/write. Just use a
>> normal journaling filesystem and fail over by mounting the FS on the
>> backup server. Consider replication such as DRDB or proprietary SAN
>> replication if you feel you must physically mirror the storage.
> 
> That means "forget about cyrus being active/active"?
> Sounds like a BIG limitation to me, especially when we talk about
> horizontal scalability.

No. You scale horizontally with Murder. Or front-end with another proxy 
like perdition, or have the clients connect to other servers directly by 
using ACAP (mostly dead), IMAP referrals (mostly unimplemented), or 
simply telling users which server to use (historically, universities 
would advertise user-specific load-balancing hostnames like 
rgraves.imap.carleton.edu). You get active/active N+1 redundancy by 
allowing failover server(s) to mount other server's filesystems in the SAN.

Anyway, it's not Exchange 5.5. It doesn't crash every week. And when you 
perform 10 times better than the competition, you have 1/10 the need for 
horizontal scalability.

> Regarding your questions, I've never tried to do comparisons between
> VxFS and ext3, but as far as I know the first one performs better. If
> this is available for Solaris 10_x86 consider an AMD64 architecture,
> should be pretty cheap compared to SPARC and very well performing.

If we were going to stay in the Solaris game I think we'd be looking at ZFS.

Interesting. 
http://www.sun.com/software/whitepapers/solaris10/fs_performance.pdf 
suggests that ext3 is better than reiserfs for their test workload. Just 
goes to show you that benchmarks are entirely parameter-dependent. 
Anyone have postmark parameters that they feel accurately reflect 
Cyrus's needs?
-- 
Rich Graves <rgraves at carleton.edu>
Sr UNIX and Security Administrator
Ofc 507-646-7079 Cell 952-292-6529