Anjan,
> Pretty soon, a PowerEdge 6650 with 4 x 2Ghz XEONs, and 8GB Memory, with
> internal drives on RAID5 will be delivered. Postgres will be from RH8.0.
How many drives? RAID5 sucks for heavy read-write databases, unless you have
5+ drives. Or a large battery-backed cache.
Also, last I checked, you can't address 8GB of RAM without a 64-bit processor.
Since when are the Xeons 64-bit?
> Shared_buffers (25% of RAM / 8KB)) = 8589934592 * .25 / 8192 = 262144
That's too high. Cut it in half at least. Probably down to 5% of available
RAM.
> Sort_mem (4% of RAM / 1KB) = 335544. We'll take about half of that -
> 167772
Fine if you're running a few-user-large-operation database. If this is a
webserver, you want a much, much lower value.
> Effective_cache_size = 262144 (same as shared_buffers - 25%)
Much too low. Where did you get these calculations, anyway?
> In a generic sense, these are recommended values I found in some
> documents.
Where? We need to contact the author of the "documents" and tell them to
correct things.
> joins, orderby, groupby clauses. The web application is based on
> Apache/Resin and hotspot JVM 1.4.0.
You'll need to estimate the memory consumed by Java & Apache to have realistic
figures to work with.
> Are the above settings ok to begin with? Are there any other parameters
> that I should configure now, or monitor lateron?
No, they're not. See:
http://www.varlena.com/varlena/GeneralBits/Tidbits/perf.html to tune these
parameters.
--
Josh Berkus
Aglio Database Solutions
San Francisco
