DL585G1 Memory Upgrade ESX 3.0 performance from PC3200 to PC2700, PC2100?

[einstein-a-go-g]

We currently have 4 x DL585G1 each with 16GB of DDR400 (PC3200) memory, 4 x 1GB modules in each server. Leaving four spare slots in each server. From what I've read I believe the recommended configuration for PC3200 (DDR400) memory is 4x2GB modules to give 32GB of PC3200 memory in a DL585. We currently need to add more memory to our VMware ESX 3.0 farm, approx 90GB.

What we propose to do is to remove 2 x 16GB kits from two other ESX servers, and upgrade the existing two occupying all 8 banks with 1G modules, and then purchasing 32GB kits for the remaining two.

Will this configuration work? i.e. all eight slots filled on all processor boards with PC3200 memory, I've read that the speed will drop, will this affect VMware ESX 3.0 performance?

Andrew

[PatrickMSlatter]

Taken from the HP Product Bulletin:

http://h18004.www1.hp.com/products/quickspecs/11902_na/11902_na.HTML

Rules:

Must install a minimum of 2 DIMMs in the processor memory board in slot 2

DIMMs on a processor memory board must be installed in pairs and in bank order

All DIMMs on a processor memory board must be of the same size (512 MB, 1 GB, or 2 GB)

Each processor memory board can have different amounts of memory, ex. Processor memory board 2 = (4) 1 GB, Processor memory board 1 = (2) 512 MB, Processor memory board 4 = no memory

PC2700 memory support requires -002 or greater processor boards

333 MHz memory performance requires no more than 6 PC2700 DIMMs per processor board; any more will result in the memory slowing down to 266 MHz

PC3200 memory, running at 400 MHz will be supported on a PC3200-only processor board (012567-001) with 4 DIMM slots, resulting in a system max of 32 GB with 4 processors

My DL 585 G1's have PC2100 DIMMs and have 8 slots per CPU board, but the one time I saw a PC3200 CPU board it had only 4 DIMM slots, which would jive with what the HP article referenced above says. If I were you I'd verify if you really do have PC3200 or 8 slots per CPU board. According to HP you can't have the config you are describing, of course it's possible that you are running PC3200 RAM in a PC2100 CPU board but that's not a supported config...

[esiebert7625]

I have 32GB in my DL585G1. I always use the faster PC3200 memory in my DL585 and DL385's. The only downside is that you can install less total memory when using PC3200 instead of PC2700. When you use 2GB PC3200 modules you max the server out at 32GB instead of 64Gb with PC2700. You can only put 4 modules in though with PC3200 memory instead of 8 with PC2700.

Also PC3200 memory is only supported on 2.6 GHz single core models and dual core models.

http://h18004.www1.hp.com/products/quickspecs/11902_div/11902_div.html#Memory

[einstein-a-go-g]

Taken from the HP Product Bulletin:

http://h18004.www1.hp.com/products/quickspecs/11902_na

/11902_na.HTML

yes, I aware of this document, and have read it many times.

My DL 585 G1's have PC2100 DIMMs and have 8 slots per

CPU board, but the one time I saw a PC3200 CPU board

it had only 4 DIMM slots, which would jive with what

the HP article referenced above says. If I were you

I'd verify if you really do have PC3200 or 8 slots

per CPU board. According to HP you can't have the

config you are describing, of course it's possible

that you are running PC3200 RAM in a PC2100 CPU board

but that's not a supported config...

We purchased our servers initially with 16GB, 4 x 1GB module per processor board. 8 2GB kits were purchased per server. According to the "recommended" HP Guide, if we want to carry on running a PC3200 configuration, we would have to bin all the memory, and replace with 2G modules, purchase 8 4GB kits, the problem with this is the memory waste and cost to us.

and we were wondering if we could do the cheaper option, and re-use the existing memory, and populate ALL slots with 1GB modules to populate to 32GB and then purchase complete kits for the others.

I was also wanting to know, any performance issues dropping from PC3200 to PC2700/2100 memory.

I suspose, I'll have to suck it and see. I'll report back.

[einstein-a-go-g]

ah!

Just opened the server and had a look.....

the processor boards only have four dimm slots per processor card! Currently filled with 1G modules per slot. 4G per processor card.

Looks like we will need to replace all the memory to take us to 32GB.

[esiebert7625]

I'm sure the performance might drop a bit, one runs at 400Mhz, the other at 333Mhz. It probably will not be all that noticeable though. Memory is typically not the biggest bottleneck when it comes to performance. The disk is usually the slowest piece.

[esiebert7625]

You do, thats what sucks, I had to throw away a bunch of memory because the servers all came with 1GB memory chips. I had to remove them and replace them with all 2GB. And unfortunately you cannot order the server without any memory.