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Old 11-18-2008, 07:52 AM
Rainer Duffner
 
Default how can I stress a server?

Rudi Ahlers schrieb:
> Hi all,
>
> I have a server, with an Intel DG35EC motherboard, Q9300 CPU, 8GB
> Kingston DDRII RAM which can't take a lot of load. I have 4 XEN VPS's
> on there, which doesn't consume more than 4GBM RAM at this stage. Yet,
> the machine sky rockets at some times. I've moved the XEN VPS's to
> another server, with 4GM RAM, and it doesn't cause the same problems.
>
> So, apart from memtest86 how else can I stress test the server to find
> out what the problem is?
>
>
>



http://oca.microsoft.com/en/windiag.asp

(Yeah, it's MSFT - but I heard good things about it - memtest is not
everything....)

I'm not sure if 8 GB and non-ECC (and non-buffered!) actually works that
well....


Rainer
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Old 11-18-2008, 08:25 AM
"Rudi Ahlers"
 
Default how can I stress a server?

On Tue, Nov 18, 2008 at 10:24 AM, John R Pierce <pierce@hogranch.com> wrote:
> Rudi Ahlers wrote:
>>
>> John, just cause the machines we use to serve web content to our
>> clients doesn't use the grade of equipment you prefer to use, and can
>> afford, doesn't mean equipment that other people use is inferior, or
>> worthless.
>>
>>
>
> ECC memory would have caught any memory errors, (including memory timing),
> and give a diagnostic and we wouldn't be having this conversation, this
> system would be in production, and you'd be working on the next customers
> job.
>
>
> oh yeah, those 'server' motherboards generally use registered/buffered
> memory, which can handle higher memory fanouts and support a full load of
> memory banks robustly.
>
>
>
> I meant to suggest the other night, go into the Intel BIOS, find the memory
> settings area, and set it to custom timings, and add a clock to each of the
> timings, like if its 4-4-4-12, try 5-5-5-15 (or whatever the next increment
> is). running 8GB on a desktop board, I'm guessing you have all slots
> full, this increseas the capacitive load on the address and data bus, and
> makes marginal timing more marginal.
>
>
> _______________________________________________


John, I know what ECC does. I have 2 Dell PE860 servers with 8GB ECC
DDRII RAM as well, and they're both giving RAM problems. I had top
swap-out the RAM 2 times with the suppliers already, and swapped out a
motherboard on the one of the servers. Honestly, ECC isn't my
favourate to use.

At the same time, I have about 8 servers with cheap Gigabyte
motherboards and non-ECC RAM, which have been running for close to 4
years now, without any hickups at all.

It's the first time I try the Intel board, since it's supposed to be a
step-up from the desktop boards, and has 4 memory slots as apposed to
only 2.


The server had the same problems when I only had 4GBM RAM (2 slots
used & 2 slots open), so I don't think that the capacitive load is the
problem here. Right now the server is still at the datacentre - which
is 2 hours drive there & back with traffic, so I'm going to get it
later today / tonight, as soon as I've moved all the data across to
the slower gigabyte server, and then I can try the RAM timings thing
in the BIOS.

But, how can I put a LOT of load onto it, and see what's causing the
problem? For all I know, the motherboard could be faulty, or the CPU,
or maybe even the SATA bus?


--

Kind Regards
Rudi Ahlers
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Old 11-18-2008, 09:34 AM
Kai Schaetzl
 
Default how can I stress a server?

Rudi Ahlers wrote on Tue, 18 Nov 2008 11:25:31 +0200:

> But, how can I put a LOT of load onto it, and see what's causing the
> problem

http://httpd.apache.org/docs/2.0/programs/ab.html
as a starter

Kai

--
Kai Schätzl, Berlin, Germany
Get your web at Conactive Internet Services: http://www.conactive.com



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Old 11-18-2008, 12:29 PM
Barry Brimer
 
Default how can I stress a server?

So, apart from memtest86 how else can I stress test the server to find
out what the problem is?


Have you looked at Inquisitor? There is a nice article about it which
includes a download link at <http://www.linux.com/articles/149774>


Hope this helps.

Barry
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Old 11-18-2008, 12:58 PM
"Filipe Brandenburger"
 
Default how can I stress a server?

Hi Rudi,

On Tue, Nov 18, 2008 at 02:13, Rudi Ahlers <rudiahlers@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
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Old 11-18-2008, 01:48 PM
"Rudi Ahlers"
 
Default how can I stress a server?

On Tue, Nov 18, 2008 at 3:58 PM, Filipe Brandenburger
<filbranden@gmail.com> wrote:
> Hi Rudi,
>
> On Tue, Nov 18, 2008 at 02:13, Rudi Ahlers <rudiahlers@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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Old 11-18-2008, 02:53 PM
"David G. Mackay"
 
Default how can I stress a server?

On Tue, 2008-11-18 at 16:48 +0200, Rudi Ahlers wrote:
> 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.

I seem to recall that one of the differences between AMD and Intel
virtualization is that AMD chips have additional memory management
capabilities that are specific to virtualization on the CPU chip, where
Intel processors require additional support circuitry. The fact that
your problems surface when you're running xen suggests that possibly the
additional support isn't functioning correctly. Is it possible that
there's some obfuscated BIOS setting that's necessary to enable it, or
that it's just not present on the motherboard?

Dave


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Old 11-18-2008, 02:59 PM
"nate"
 
Default how can I stress a server?

Rudi Ahlers wrote:
> Hi all,
>
> I have a server, with an Intel DG35EC motherboard, Q9300 CPU, 8GB
> Kingston DDRII RAM which can't take a lot of load. I have 4 XEN VPS's
> on there, which doesn't consume more than 4GBM RAM at this stage. Yet,
> the machine sky rockets at some times. I've moved the XEN VPS's to
> another server, with 4GM RAM, and it doesn't cause the same problems.
>
> So, apart from memtest86 how else can I stress test the server to find
> out what the problem is?

I think I mentioned this already but I use the Cerberus test suite

http://sourceforge.net/projects/va-ctcs/

Haven't had to use it in a while but works quite well, a lot of
big OEMs use it as well for their burn in tests. For me it found
problems much faster than memtest86. Apparently it was developed
by VA Linux(If your familiar with that name)

Been meaning to setup a pxe linux boot environment with this in
there so I can run it without the full blown OS on there, but
haven't had a chance yet.

nate


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Old 11-18-2008, 08:44 PM
"Rudi Ahlers"
 
Default how can I stress a server?

> I think I mentioned this already but I use the Cerberus test suite
>
> http://sourceforge.net/projects/va-ctcs/
>
> Haven't had to use it in a while but works quite well, a lot of
> big OEMs use it as well for their burn in tests. For me it found
> problems much faster than memtest86. Apparently it was developed
> by VA Linux(If your familiar with that name)
>
> Been meaning to setup a pxe linux boot environment with this in
> there so I can run it without the full blown OS on there, but
> haven't had a chance yet.
>
> nate
>
>
> _______________________________________________

Thanx nate, I'll check it out

--

Kind Regards
Rudi Ahlers
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Old 11-18-2008, 08:47 PM
"Rudi Ahlers"
 
Default how can I stress a server?

> I seem to recall that one of the differences between AMD and Intel
> virtualization is that AMD chips have additional memory management
> capabilities that are specific to virtualization on the CPU chip, where
> Intel processors require additional support circuitry. The fact that
> your problems surface when you're running xen suggests that possibly the
> additional support isn't functioning correctly. Is it possible that
> there's some obfuscated BIOS setting that's necessary to enable it, or
> that it's just not present on the motherboard?
>
> Dave
>
>
> _______________________________________________

Hi Dave,

My experience & knowledge of AMD is limited, so I stick to what I
know, Intel. The only setting I know of in the BIOS related to
virtualization is Intel's VT - which is enabled. But even when it was
disabled I had the problem. I only enabled it last week to see if I
could install FreeBSD as a fully virtualized guest.


--

Kind Regards
Rudi Ahlers
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