On Thu, Oct 16, 2008 at 7:22 AM, Roberto Scattini
<roberto.scattini@gmail.com> wrote:
> hi everybody:
>
> in a couple of days i will reinstall an offline database server. It's
> a old HP Proliant DL580 G3 with three disks (147 GB each). Currently
> it has a debian Sarge in a RAID5 hardware array ( with HP Smart Array
> 6i, [RAID bus controller: Compaq Computer Corporation Smart Array 64xx
> (rev 01)] ).
Does that controller have battery backed cache?
> i googled a while and get to this page:
> http://www.powerpostgresql.com/PerfList , so my first question is,
> this document and the tips given hasn't been deprecated by now, right?
It's a little old but most of it holds true.
> then:
> -is raid5 the worst election in this scenario (three disks)?
Yes
> -which is the best (and with that i mean secure in first place and
> with more perfomance in second) possible configuration achievable with
> this three disks?
either 2 disk mirror w hot spare or 3 disk mirror if the controller supports it.
> -should i ask my boss to buy another disk? (it will be difficult, but
> if i can demonstrate It worth it...)
Yes you should.
> i think i will "Separate the Transaction Log from the Database" with
> two RAID1 arrays (if they buy the new disk). is this a good way to go?
> it would be too bad if i put the logs in a disk without RAID? (only if
> i dont get the new disk...)
If the controller has battery backed cache, then go with a single
RAID 1+0 unless it's really write heavy raid 1+0 will probably be a
better choice. Do not use a single disk w no raid.
> our application (running on separate webserver) is of the type "OLTP",
> the server will be entirely dedicated to postgresql. i will configure
> a warm-standby server, so the WAL files will be forwarded to another
> server.
You should benchmark with two RAID 1s and a single RAID1+0.
