Re: Upgrade OS from Redhat AS3 (2.4 kernel) to AS4 (2.6)

Roger Hand wrote:

> Due to performance issues (which I wrote about on pg-performance list)
> we will be upgrading our Redhat AS3.0 box (kernel 2.4) to Redhat AS4
> (kernel 2.6) in order to take advantage of the better I/O that the 2.6
> kernel offers. (I say upgrading but actually we'll wipe the box and
> start fresh.)
>
> We are running Postgres 8.0.3.
>
> I had assumed we would have to backup/restore the entire db, but I got
> to wondering if it would be possible to simply point the new Postgres
> install to the existing db (the data itself is on a separate drive
> array) and be back up and running without the time to do the restore.

Yes as long as you are not switching architectures (say to x86_64) or
filesystems you should be fine. I assume you will be running 8.0.3
on the new system as well.

>
> Is this a relatively simple matter? Or is it too hazardous and tricky
> to bother with?

Not hazardous at all as long as you don't accidently format the
filesystem ;). Make a tar backup just in case.

>
> If it's possible I'd appreciate a list of what I'd need to save off
> the old drive, where the os and Postgres program itself lived.

Nothing. The postgresql.conf and pg_hba.conf will reside in the data
directory so it will be fairly independent. Note
that I am ONLY talking about postgres here. You may want to save things
from the OS for other reasons.

>
> Also: Anything to watch out for with Postgres on 2.6 kernel as opposed
> to 2.4? Any settings that should be different? We've been advised to
> try "elevator=deadline". We write pretty much 24 hours a day, and have
> I/O issues!

Well 2.6 is pretty solid but I wasn't part of the thread so I can't tell
you if this will solve your problem. I can
say that overall 2.6 is much better for databases.

Sincerely,

Joshua D. Drake
Command Prompt, Inc.

>
> -Roger