vPar and dual-core CPU question

[Jimmy Tom_2]

For the dual core PA8800 and PA8900 CPUs. If there are two vPar environments, one on each of the core. What happen if one of the core fails? Will it take down the other core, thereby, bring down the other vPar?

thanks in advance.

[Pete Randall]

Jimmy,

This is pure conjecture on my part, but I wouldn't think you'd be able to split a dual core between two VPARs. I would think they would have to be assigned in pairs.


Pete

[Jimmy Tom_2]

Is advertise that each CPU can have its own vPar environment. a 8 CPU rp7420 server can have 8 vPars, taking the I/O out of the equation.

[Duncan Edmonstone]

It very much depends where the processor fails - there are shared components on the sockets, so it is *possible* for a failure to take down both cores, its also *possible* that one will stay working

HTH

Duncan

[Fred Ruffet]

I believe that each CPU can be affected to any vPar. I've been using CPU allocation on a superdome with lots of CPU and I don't remember of such a limitation.

In a security way, I would say that you'd even better split dual cores to limit points of failure : if you have 2 vPars and 2 dual cores, I would go for 1 CPU of each dual core on each vPar. In such a way, even if the internal bus of one dual core burns, each vPar still have one CPU left... On the other hand, there may be less perfs, but I don't think it is significant.

Regards,

Fred

[Pete Randall]

How are the two cores addressed? Each VPAR has to own everything on any one given Local Bus Adapter. That's why I figured that you couldn't split them.


Pete

[Pete Randall]

I stand corrected. According to "Installing and Managing HP-UX Virtual Partitions":

"With the PA-8800s and future dual-cores, there are two CPUs per socket. (On a cell board with four sockets, this allos 8 CPUs per cell board). The CPUs that share the socket are called sibling CPUs.

Splitting sibling CPUs across virtual partition refers to assigning one sibling CPU to one partition and assigning the other sibling to a different virtual partition."

And, in another note from the same document:

"The PA-880s are dual-core sockets: they have two CPUs per socket. Deactivation happens on a processor level, but deconfiguration happens at the socket level. If a socket is deconfigured, both processors sharing the socket will be unavailable."


Pete

[Tim D Fulford]

Hi

HP have never reccomended having less than 2 CPUs in a vPAR. for either PA8700 or PA8800 (PA8900 is not in production .... yet)..

In one of your previous replies you implied (or I infered) that rp7420 is a 8 CPU system....

rp7420 can have up to 16 CPUs these 16 CPS sit on 8 sockets. these CPUs are the PA8800 with 32MB shared L2 cache...... Where as the rx7620 (which is the same chassis backplane and so on as rp7420) can have 8CPUs on 8 sockets using the Itanium II CPUs... And with the new mx2 (dual core) you can have up to 16CPUs on 8 sockets...

Regards

Tim