topic Re: DL580G2 Multi-Processing vs Single Processor in Operating System - Linux

DL580G2 Multi-Processing vs Single Processor

sputnix — Thu, 20 Jan 2005 08:44:25 GMT

I have a DL580 G2 Server with 4 CPUs 3.0 MHz, still wanted to downgrad to one CPU. OS running SLES 8 Kernel Version 2.4.21-138-smp. After the remove of 3 CPUs, the server does´t boot into OS. The server is stopping the boot process by loading the CISS-driver.
Putting a second CPU back, the server is booting without any problem.

First the HP Support Center told me it is unsupported to run only 1 CPU of this type in this server. I wanted to have this statement via mail, HP turned around and told me, the server must be able by running with only 1 CPU.

The Problem is that the server only runs with 1 CPU if smp is disabled. This means no hyperthreading is activated and I got a performance loose of 30%. Bad for the customer.

Does anybody know why 1 CPU in a DL580G2 server is only running when smp is disabled? Or is it possible?

There is nothing available on HP website, where I can find informations about the support of one CPU. The statement of HP is: there is no reglementation in any paper, so it is supported!

thx for answers
andrea

Re: DL580G2 Multi-Processing vs Single Processor

Kodjo Agbenu — Fri, 21 Jan 2005 19:10:04 GMT

Hi Andrea,There is no reason that SMP kernel fails on mono-cpu server. Have you tried to update the SLES8 kernel ?Good luck.Kodjo

Re: DL580G2 Multi-Processing vs Single Processor

sputnix — Sat, 22 Jan 2005 02:12:39 GMT

Hi Kodjo,
there is no reason, yes! But it doesnÂ´t function.
Sure, there are newer kernels with smp-fixes, but I have a reglementation for the application for using this.

thx for your reply,
andreas

Re: DL580G2 Multi-Processing vs Single Processor

Ross Minkov — Sun, 23 Jan 2005 23:24:57 GMT

Have you tried booting to a non smp kernel when with only one CPU. You shouldn't have to turn off HT in RBSU.

Regards,
Ross

Re: DL580G2 Multi-Processing vs Single Processor

sputnix — Mon, 24 Jan 2005 07:47:42 GMT

Hi Ross,

we didnÂ´t disable hyperthreading in the RBSU!
We installed another kernel without smp and the server was booting.
So we disabled multiprocessing functionality in the OS not in the bios, but we want to have hyperthreading functionality because of the performance!!!

regards
andreas

Re: DL580G2 Multi-Processing vs Single Processor

sputnix — Thu, 27 Jan 2005 09:48:56 GMT

this is known problem with the SUSE Kernel below 2.4.21-198

Solution: Update to a newer kernel version (maybe update of the cciss driver from HP is also required ==> check kernel dependencies on the HP download website)

http://support.novell.com/cgi-bin/search/searchtid.cgi?/en/2003/12/sp3_hp_machines.html

http://h18007.www1.hp.com/support/files/server/us/download/22167.html

==> newest driver for the Smart Array Controller

call closed!
andreas

Re: DL580G2 Multi-Processing vs Single Processor

sputnix — Thu, 27 Jan 2005 09:51:17 GMT

thx!

andreas