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-ar
chive.com/dbmail dbmail.org/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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