Hi everyone, thankyou for your responses. I'll try to address everyone's
comments in the one email.
I agree with Stephen. How many servers are there? Maybe a SAN with
SCSI or SAS drives would make even more sense in that case. They'll be
sitting in the same rack anyway. Correct?
Unfortunately we already have the machines, they are 1U with two 160Gb
SATA disks, 2.5Gb RAM with 3GHz CPU. We have three identical machines
with 2xGb ethernet, we'll be using one for crossover to keep the data in
sync between two of them and the other to connect to the network. I've
got dbmail running on all three, and MySQL data is shared via a drbd and
managed with heartbeat between two of them.
I had chosen MySQL because it was what dspam and postfix-policyd uses,
but I'm open to running both MySQL and Postgres (maybe split them up
between the servers) if Postgres is a good choice for running the
DBMail. (I just looked and dspam can use postgres also but maybe it's
better to split these databases up between servers)
IIRC it was possible to give InnoDB a raw partition and it would live
on it happily by itself, so you would loose the operating system's
filesystem overhead. Alas I have never done that with mysql/InnoDB,
only Informix. So I don't know how much if at all it helps.
I also have had experience with Informix, and the current stats
(according to their mailing list) is that raw partitions don't make much
difference in speed unless you have limited RAM for caching.
Also, 10k users would be POP3 only or do they have IMAP too? How many
servers and with what configuration have you planned? I'm just curious
here, as my biggest dbmail install is only ~600 IMAP users.
Only a few dozen use IMAP, the rest are all POP3. The 10k users is a bit
misleading also, I just got some stats from our current mailservers
(they use vpopmail with NFS backend) and we're only delivering about
20-25k emails per day. So the majority of our users are idle. I just
checked the number of POP3 logins and it's around 145k per day. So again
not too high an average load. Our total mail store is around 35Gb.
> Actually we use SATA, in RAID5 with XFS. With just not 10K users.
Works like a charm.
> However we're on Postgres, not mysql.
I've been using XFS for years and have found it really good. I just
haven't compared it to ext3 for database files. I figure that reiserfs
wouldn't be a real option as it was designed for small files rather than
large db files. In my early testing I did install Postgres 8.2 on a
spare ubuntu machine but it didn't seem to give the performance benefits
that an earlier post on this list suggested over the MySQL 5.0
(http://www.mail-archive.com/[email protected]/msg10752.html). If I do
go for Postgres it will be version 8.1.8 as that's what is currently
shipping with Debian Etch (but I will compile 8.2 especially for the
purpose if it is worth it). Do you have some tips on the setup of
postgres for dbmail? It would be fantastic if I could get the same
performance as what was suggested in that post!
Only other tip I'd make for the OP is to look at one of the other
HA/Load balance schemes to get the most benefit from your servers
otherwise your second server is just going to be making heat until you
have a failure. Better off using that to improve performance in the 99%
of the time everything is working.
If I had postgres running on one server and mysql on the other, this
would be a perfect solution IMO. Just deciding on whether the added
complexity of running two db's is worth it.
Thanks again for all your comments,
Josh.
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