N4000 (A3639A and A3639B) memory question

[doris grady]

I understand that the memory cards will work between N4000 A and B and up to 32gb is supported within each system. I have several As and Bs and I want to switch memory from As to Bs or vice-versa depending on where I need it for my applications. Is this easy enough to do or is there a gotcha? Does the fact that all of my As and Bs have 8 CPUs mean that they all have 2 boards already and that all we need to do is add memory chips? I really need to know how the memory is actually configured (ie. boards, chips) Thanks.

[Sameer_Nirmal]

Inter-changing of the memory modules between As and Bs depends on your current requirements of applications running on them.
So if you have done that assessment already ( I bet you did ) , then you can inter-change that memory modules.

You can run CSTM utility to get information of the servers
Run cstm -> select all -> infolog
the infolog will give you all details of the memory slots besides other information.

Another way is to connect to GSP annd get the installed hardware information.
Remember you have to install memory modules
evenly among memory carriers.

Please refer the hardware installation doc which you may have. You can refer the following doc as well.

http://docs.hp.com/en/3687/rp7400_customer_hardwaremanual.pdf

[doris grady]

Thanks for your reponse. When I do a CSTM command, it results in the information below. Can you translate it for me? Is this saying that there are 4 slots and each slot supports 1 DIMM. Each DIMM holds up to 8 memory chips? Can I move a memory chip to another N4000 or must I replace the entire DIMM? Thanks.

Basic Memory Description

Module Type: MEMORY
Total Configured Memory : 12288 MB
Page Size: 4096 Bytes

Memory interleaving is supported on this machine and is ON.

Memory Board Inventory

Ext
Slot Conf./Slot label for each DIMM (MB)
Number

0a 2a 1a 3a 3b 1b 2b 0b
EXT0 512 512 512 0 0 512 512 512
EXT1 512 512 512 0 0 512 512 512
EXT2 512 512 512 0 0 512 512 512
EXT3 512 512 512 0 0 512 512 512

[Torsten. · Accepted solution]

Hi Doris,

something about the wording first:

a DIMM is a component that holds the integrated circuit. In this case, 2 DIMMs resulting in a memory MODULE. 2 Memory DIMMs have to be installed as a pair in 2 corresponding slots (e.g. 0A/0B) on a CARRIER. Your system has 4 memory carriers installed, each with 2 available slots. So you are able to add up to 8 new DIMMS (4 Modules) to your system.

-OR-

you can remove several modules from your system (e.g. 2A/2B from every carrier = 4GB memory).

[Sameer_Nirmal]

DIMM is a memory module having chips as integrated circuits on both the side of the module. It is not slot as you are assuming.

You have 4 memory carrier boards installed on slots Ext0-Ext3 . These slots are then interfaced with system board at the backend.
Each memory carrier board has 8 slots numbered 0a 2a 1a 3a 3b 1b 2b 0b. On these slots DIMMs are paired and numbered 0a/b, 1a/b, 2a/b, 3a/b. You have all 512MB DIMMs installed. 3a/b pair on each carrie board is free.

For DIMMs to work , both DIMMs in a pair slot must be of same type i.e. same part number. We need to fill up the pair at a time, not just one Module in a lot . Since the Memory interleaving is ON , maintain DIMMs evenly among the carriers ( even if you are trying to remove additional memory from servers )i.e fill first pair of carries 0 , 0a/b and then first pair of carrier 1 , 0a/b and so on. This will ensure best performance

Maintain the slot order on each carrier board as 0a/b , 1a/b, 2a/b , 3a/b.

Just ensure all above to avoid any troubles like PDC errors .