On Fri, 2006-04-07 at 14:59, Gavin Hamill wrote:
> On Fri, 07 Apr 2006 13:54:21 -0500
> Scott Marlowe <smarlowe@g2switchworks.com> wrote:
>
> > Are the same queries getting the same basic execution plan on both
> > boxes? Turn on logging for slow queries, and explain analyze them on
> > both machines to see if they are.
>
> See reply to Tom Lane :)
I didn't see one go by yet... Could be sitting in the queue.
> They probably would if this had been bought new - as it is, we have
> rented the machine for a month from a 2nd-user dealer to see if it's
> capable of taking the load. I'm now glad we did this.
Thank god. I had a picture of you sitting on top of a brand new very
expensive pSeries
Let us know if changing the fsync setting helps. Hopefully that's all
the problem is.
Off on a tangent. If the aggregate memory bandwidth of the pSeries is
no greater than you Xeon you might not see a big improvement if you were
memory bound before. If you were CPU bound, you may or may not see an
improvement.
Can you describe the disc subsystems in the two machines for us? What
kind of read / write load you have? It could be the older box was
running on IDE drives with fake fsync responses which would lie, be
fast, but not reliable in case of a power outage.
Do you have hardware RAID for your pSeries? how many discs, how much
battery backed cache, etc?
> Multi-Opteron was the other thing we considered but decided to give
> 'Big Iron' UNIX a whirl...
It still might be a good choice, if it's a simple misconfiguration
issue.
But man, those new multiple core opterons can make some impressive
machines for very little money.