Re: how to configure my new server

Phillip,

First, a disclaimer: my advice is without warranty whatsoever. You want a
warranty, you gotta pay me.

> I've a new configuration for our web server
>
> Processor Processeur Intel Xeon 2.0 Ghz / 512 Ko de cache L2
> Memoiry 1 Go DDR SDRAM
> Disk1 18Go Ultra 3 (Ultra 160) SCSI 15 Ktpm
> Disk2 18Go Hot Plug Ultra 3 (Ultra 160) SCSI 15 Ktpm
> Disk3 18Go Hot Plug Ultra 3 (Ultra 160) SCSI 15 Ktpm
> Disk4 18Go Hot Plug Ultra 3 (Ultra 160) SCSI 15 Ktpm
> Disk5 36Go Hot Plug Ultra 3 (Ultra 160) SCSI 15 Ktpm

No RAID, though?

Think carefully about which disks you put things on. Ideally, the OS, the
web files, the database files, the database log, and the swap partition will
all be on seperate disks. With a large database you may even think about
shifting individual tables or indexes to seperate disks.

> linux values:
> kernel.shmmni = 4096
> kernel.shmall = 32000000
> kernel.shmmax = 256000000

These are probably too high, but I'm ready to speak authoritatively on that.

> postgresql values:
> shared_buffers
> max_fsm_relations
> max_fsm_pages
> wal_buffers
> wal_files
> sort_mem
> vacuum_mem

Please visit the archives for this list. Setting those values is a topic of
discussion for 50% of the threads, and there is yet no firm agreement on good
vs. bad values.

Also, you need to ask youself more questions before you start setting values:

1. How many queries does my database handle per second or minute?
2. How big/complex are those queries?
3. What is the ratio of database read activity vs. database writing activity?
4. What large tables in my database get queried simultaneously/together?
5. Are my database writes bundled into transactions, or seperate?
etc.

Simply knowing the size of the database files isn't enough.

--
Josh Berkus
Aglio Database Solutions
San Francisco