Re: [PERFORM] Quad processor options

scott.marlowe wrote:

> Well, from what I've read elsewhere on the internet, it would seem the
> Opterons scale better to 4 CPUs than the basic Xeons do. Of course, the
> exception to this is SGI's altix, which uses their own chipset and runs
> the itanium with very good memory bandwidth.

This is basically what I read too. But I cannot spent money on a quad
opteron just for testing purposes :)

> But, do you really need more CPU horsepower?
>
> Are you I/O or CPU or memory or memory bandwidth bound? If you're sitting
> at 99% idle, and iostat says your drives are only running at some small
> percentage of what you know they could, you might be memory or memory
> bandwidth limited. Adding two more CPUs will not help with that
> situation.

Right now we have a dual xeon 2.4, 3 GB Ram, Mylex extremeraid
controller, running 2 Compaq BD018122C0, 1 Seagate ST318203LC and 1
Quantum ATLAS_V_18_SCA.

iostat show between 20 and 60 % user avg-cpu. And this is not even peak
time.

I attached a "vmstat 10 120" output for perhaps 60-70% peak load.

> If your I/O is saturated, then the answer may well be a better RAID
> array, with many more drives plugged into it. Do you have any spare
> drives you can toss on the machine to see if that helps? Sometimes going
> from 4 drives in a RAID 1+0 to 6 or 8 or more can give a big boost in
> performance.

Next drives I'll buy will certainly be 15k scsi drives.

> In short, don't expect 4 CPUs to solve the problem if the problem isn't
> really the CPUs being maxed out.
>
> Also, what type of load are you running? Mostly read, mostly written, few
> connections handling lots of data, lots of connections each handling a
> little data, lots of transactions, etc...

In peak times we can get up to 700-800 connections at the same time.
There are quite some updates involved, without having exact numbers I'll
think that we have about 70% selects and 30% updates/inserts.

> If you are doing lots of writing, make SURE you have a controller that
> supports battery backed cache and is configured to write-back, not
> write-through.

Could you recommend a certain controller type? The only battery backed
one that I found on the net is the newest model from icp-vortex.com.

Regards,
Bjoern