I don't think there is any need to take this off list, I think there are
lot of people who would like to hear this discussion. Anyway I don't
run a dbmail site with that much load, however I to have a fair amount
of experience running PostgreSQL.
1) Never vacuum FULL: If you are vacuuming often enough, you should
never need vacuum full. It is totally normal to have some slack space
in a table, and in fact it can be better for performance to have some
slack space since the DB doesn't have to allocate additional table space
to insert or update a row.
2) Autovacuum can be help here (Full disclosure note: I wrote the
contrib autovacuum tool for postgresql), it help by only vacuuming
tables when you need it, so you both vacuum tables that to need it
frequently avoiding the need for vacuum full and it doesn't needlessly
vacuum tables that don't need it (messageblks for example) which can
save a lot of cycles. One limitation of autovacuum in 8.0 is that you
can't set different vacuuming thresholds on a pertable basis, this is
solved in 8.1 with the fully integreated (not contrib) version of
autovacuum introduced in 8.1.
3) Slony is probably the best replication solution if you don't need
multi-master.
4) I just back nightly, that may not be sufficient for most people. I
just pg_dumpall | bzip -9 > backup_file.bz, and make sure that backup
file gets into the rest of the backup system.
5) Running the latest 2.0.x DBMail, I still have it get out of whack
every once in a while where it won't accept connections anymore etc... I
would really love to see the xinetd patch backported to 2.0.
Matt
Niblett, David A wrote:
I'm hoping that someone on the list can help me sort out
what I hope I'm doing wrong. Our group seems to be devoting
a lot of time and heartache to running dbmail for our user
base. Granted a lot seems to be database related.
So if there is anyone on the list that is using dbmail 2.0
with PostgreSQL (8.x) with 5k+ users, and a data set of around
20G would you contact me off list if you like.
The items I really interested in:
- How/if you backup or replicate your database
- How you deal with vacuum's (mine seem to take forever)
- How/if you deal with a vacuum FULL.
- What kind of schedule you use for dbmail-util
- The number of connections you have from dbmail and what kind
of load that produces.
- What kind of "bad things" happen to DBMail when your database
load gets rather high.
I know a lot of my questions will be PostgreSQL related, and
not DBMail related, but I'm hoping to find someone in the same
type of setup like I have to lower the interpolation that may
have to be done.
I was using slony1 to replicate my database, but that was
using excessive disk space in the database and eating up a
lot of memory. If I don't run with Slony1, then it seems
everything works great, but I'm trying to plan for a free webmail
type site that may greatly grow in size.
Thanks.
--
David A. Niblett | email: [EMAIL PROTECTED]
Network Administrator | Phone: (352) 334-3400
Gainesville Regional Utilities | Web: http://www.gru.net/
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