FWIW, 7.4.6 is a binary, drop-in place upgrade for 7.4.2. And 7.4.2 has known bugs. However, I understand your situation.

As soon as we get the go-ahead, I will upgrade. I think the company is actually looking towards 8.0 certification.

Okay, thanks. Even with 7-disks? I trust that.

Well, it's less bad with 7 disks than it is with 3, certainly. However,there is an obvious and quick gain to be had by splitting off the WAL logs onto their own disk resource ... up to 14%+ performance in some applications.

Pardon my ignorance, but the WAL logs are comprised of pg_xlog and pg_clog? Their own disk resource, but not within the same channel of disks the database is on, right?

So, RAID 1+0 (sw) is probably the best option. I've run sw RAID personally for years without
issue. I am a bit hesitant in doing sw RAID for a production server for
a database --- probably because its not my server. Any thoughts on sw
RAID for Postgresql?

Yes. See my article for one. In generaly, SW RAID on BSD or Linux works well for PostgreSQL ... UNLESS your machine is already CPU-bound, in which case it's a bad idea. If you're hitting the CS bug, it's definitely a bad idea, because the SW RAID will increase context switching.

So if your choice, on your system, is between sw RAID 10, and hw RAID 5, and you're having excessive CSes, I'd stick with the HW RAID.

Okay. InCPU-bound servers, use hw RAID. Any hw raids to avoid?

Okay. Darn. While I don't write the queries for the application, I do
interact with the company frequently. Their considering moving the
queries into the database with PL/pgSQL. Currently their queries are
done through ProvIV development using ODBC. Will context switching be
minimized here by using PL/pgSQL?

Won't make a difference, actually. Should improve performance in other ways, though, by reducing round-trip time on procedures. Feel free to recommend the company to this list.

I think their too busy to monitor/watch this list. Not a put-down to them, but I have to do my own leg work to help decide what we're going to do.

Dual Xeon 2.8 CPUs with HT turned off.

Yeah, thought it was a Xeon.

If we went with a single CPU, like Athlon/Opertron64, would CS storming go away?


Steve Poe

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