[CentOS] how can I stress a server?

Rudi Ahlers rudiahlers at gmail.com
Tue Nov 18 14:48:17 UTC 2008


On Tue, Nov 18, 2008 at 3:58 PM, Filipe Brandenburger
<filbranden at gmail.com> wrote:
> Hi Rudi,
>
> On Tue, Nov 18, 2008 at 02:13, Rudi Ahlers <rudiahlers at gmail.com> wrote:
>> ...which can't take a lot of load...
>> ...the machine sky rockets at some times...
>
> The problem you have is that the Load Average is too high?
>
> If that is indeed your problem, there is no way that this can be a
> memory or CPU issue, since those would cause crashes and not high Load
> Average.
>
> If what you have is high Load Average, check this:
> - Your machine has 8GB RAM. Are you using the 64-bit version of
> CentOS? There would be an overhead in using a 32-bit PAE version on a
> machine with more than 4GB, last time I tried it (some years ago) the
> overhead was big enough to make a difference in the server's
> performance.
> - Your machine has SATA. If you don't use the correct SATA settings on
> the BIOS, CentOS may use it in a backwards compatible mode and you
> will not get enough performance out of it (see previous posts on
> problems on SATA and on AHCI). If that's the case, changing the BIOS
> settings might make a huge difference, but beware that if you do your
> machine may no longer boot with the OS you installed right now. Better
> thing to do would be to reinstall it once you found the right setting.
>
> And next time, please state your problem clearly ("high Load Average")
> instead of jumping the gun and saying you have a CPU or RAM issue
> which does not seem to be the case here.
>
> HTH,
> Filipe
> _______________________________________________


Hi Flippie,

I have checked the BIOS settings, purely cause the new HDD was
installed on a machine withou AHCI settings, so I had to change the
settings in the BIOS to nativ IDE mode (the only other mode this
motherboard supports).

The reason why I'm suspecting the MB / RAM / CPU is that I already
swapped the HDD's out, and reinstalled CentOS - first it was x64, now
it's i386 (well, i686 as per uname -a). The only serivce that runs on
the host node is HyperVM (which include the XEN tools, PHP, Apache,
MySQL.


I have the exact same setup on a few other machines, using Gigabyte
motherboards + 4GB RAM. Other than that, the HDD's are the same, the
OS is the same, and HyperVM is the same. I basically run yum upgrade
once a week on all the machines. The only difference is this one has
an Intel DG35EC motherboard with a Q9300 Quad Core CPU on it, which is
supposed to be more power efficient than some of the Core 2 Duo CPU's
on the other machine.

As a matter of interest, all 5 Virtual Machines have been running on a
Gigabyte motherboard + i6450 CPU + 4GB RAM since yesterday, and it's
very very stable.


So, my thinking is, it's the motherboard. It could also be the RAM,
but I'm not 100% sure yet. The machine had 4GB initially, and then I
added another 4GB hoping the problem would go away, but it didn't.


-- 

Kind Regards
Rudi Ahlers


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