Superdome memory question

[Jimmy Tom_2]

Can anyone tell me what is the current highest density memory for the PA-Risc version of the SD cell? The config guide is telling me 512MB, which is 16GB per cell. The rp8400 already has 2GB dimm, which gives a total of 32GB per cell. Also, can different size memory be mixed in the same cell board?

thx in advance

[Jeff Schussele]

Hi Jimmy,

Everything I'm finding still shows 512 MB DIMMS.

Memory maxes are as follows:

16 way => 64 GB
32 way => 128 GB
64 way => 256 GB

And although I'm not positive, I'm fairly sure you can't mix DIMM sizes on cell boards. If you did, you'd have performance loss (non-optimal interleaving) are even have addressing holes.

Rgds,
Jeff

[Chung, jin-won]

Hi Tom
in fact, the highest density dimm size is 2GB. And You can mix different size of dimm module but must use a set of 4 dimms in PA-RISC superdome.

[Pedro Rubio]

Hi Jimmy,

Just 512MB dimms are supported for Superdome cells with PA-RISC PA8700 and PA8700+. For new PA-RISC PA8800 cells (Integrity Superdome) 1GB dimms support will be added.

Regards,
Pedro.

[Jimmy Tom_2]

If the Superdome can't mix their memories. Does this rule also apply to the rp8400? The rp8400 have 512mb, 1GB and 2GB dimms. It would be a waste if the 512mb dimm had to be thrown out if I wanted to use the higher density dimms.

thx

[Pedro Rubio]

Hi Jim,
RP8400 does allow you to mix different dimms sizes (512MB,1GB and 2GB) on the same cell. Of course, they must be installed on quads of the same size.

Besides, for performance reasons (interleaving), it is recommended(not mandatory) to have the same memory configuration on cells belonging to a hard partition.

Regards,
Pedro.

[Jimmy Tom_2]

Pedro,

I was told that you can't mix different memory size in the same cell board. Where can I find some reference material on this.

thx

[Pedro Rubio · Accepted solution]

Jim,

You can find these information on this document:
http://www.hp.com/products1/servers/rackoptimized/rp8400/rp8400infolib/rp8400_whitepaper.pdf

On page 10 you will read:
The minimum cell configuration includes two active CPUs and 1 GB of memory per cell board. The maximum configuration includes four active CPUs and 16 GB of memory per cell board. Memory DIMM modules for the rp8400 are sold in sets of four (quads), with DIMM sizes of 256 MB, 512 MB, and 1 GB available. Memory quads of different sizes can be mixed within a chassis and within a cell. However, for optimum memory interleaving and performance, it is recommended that one memory size be selected and distributed evenly across available cells.

Note: actually, 2GB dimms are also supported for rp8400.

Regards,
Pedro.

[Jeff Schussele]

Hi Jimmy,

I would again echo the earlier post that as of *right now* only 512 MB DIMMS are supported on the 'Domes. And that even though you can mix DIMM types on cell boards, I would definitely NOT recommend it.
There are enough cell boards in 'Domes that it's not difficult to get to the amount you want with 512 MB DIMMS.

Rgds,
Jeff

[Jimmy Tom_2]

Sorry Jeff, the mixing of the memory was for the rp8400.