DL580G2 Multi-Processing vs Single Processor

[sputnix]

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

[Kodjo Agbenu]

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

[sputnix]

Hi Kodjo,
there is no reason, yes! But it doesn´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

[Ross Minkov]

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

[sputnix]

Hi Ross,

we didn´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

[sputnix]

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

[sputnix]

thx!

andreas