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Upgrade DL380 G6 with memory for max performance

BWet
Occasional Visitor

Upgrade DL380 G6 with memory for max performance

I want to upgrade 2 of our GL380 G6 servers with new memory.

 

Speed is the highest priority so it would seem best to use 3 channels per socket (2 sockets in use) (use all available slots, a total of 18 4GB modules 1333MHz DDR3 Mirrored, lock-step)

 

I would like to have 72GB memory installed in the server (18*4gb)

However, when i run the memory config tool it suggest the following:

 

Qty 4 of HP Option Part # 500656-B21

HP 2GB 2Rx8 PC3-10600R-9 Kit
(HP Module Part # 500202-061)

 

Qty 8 of HP Option Part # 604506-B21
HP 8GB 2Rx4 PC3L-10600R-9 Kit
(HP Module Part # 605313-071)
 
P1
1G500202-061
2D605313-071
3A605313-071
4H500202-061
5E605313-071
6B605313-071
7I[empty slot]
8F[empty slot]
9C[empty slot]
P2
1G500202-061
2D605313-071
3A605313-071
4H500202-061
5E605313-071
6B605313-071
7I[empty slot]
8F[empty slot]
9C[empty slot]
 
This doesn't look like an optimal configuration. The tool won't let me force it to use 3 channels.
 
Is it possible what i want, or is this really the best way to go?
 
2 REPLIES
waaronb
Respected Contributor

Re: Upgrade DL380 G6 with memory for max performance

For mirroring, I believe it mirrors channel 1 and 2, which must be populated exactly the same, and the 3rd channel has to be empty. For both CPUs. I think the config can be different between CPU 1 and CPU 2 channels, as long as channel 1 and 2 on the same CPU are identical.

With the config you're showing, you have 2x8 + 1x4 modules per channel = 20 GB. Mirrored across channels 1 and 2, and then the same on CPU #2 so that's only 40 GB total RAM if you're mirroring.

There are also speed limitations. If you want the full 1333 MHz you'll need to leave channel 3 empty anyway and only use dual-rank modules.

Even if you used 8GB dual-rank modules, you'll fill out channels 1 and 2 of each CPU meaning 8GB x 12 modules = 96 GB. Divide by 2 if you want to mirror and that leaves you with 48GB.

The only way I can see you getting to 72 GB with mirroring is if you go to the quad-rank 16GB modules, but then your max speed will be 800 MHz with 2 channels in use, and you're only allowed 8 ranks per channel, so there you are, you only get 2x16GB per channel. If mirroring is a requirement, then channel 3 has to be empty and you're limited to just 64GB total after mirroring.

See the quickspecs memory chart which explains all of that.

Is there some business need for mirroring, like this is a critical financial system? if not, I'd suggest just lockstep mode if you wanted to go a bit beyond the normal Advanced ECC. Then you can do those 8GB x 12 modules, use lockstep mode, have 96GB of memory and run at 1333 Mhz.

In other words, 72GB of mirrored memory at 1333 MHz just isn't an option on the G6 models. You might find some off-brand 32GB modules, quad-rank, but then HP won't see them as official "smart memory" and lockstep/mirror mode won't be available, I don't think. Which is kind of lame on their part... but oh well.

I don't think the G6 supports the official HP 32GB modules since those are LRDIMMs... that's on the Gen8 models.
BWet
Occasional Visitor

Re: Upgrade DL380 G6 with memory for max performance

THe system is redundant so we can do without mirroring if this improves performance.

 

This option seems like the right one:

Is there some business need for mirroring, like this is a critical financial system? if not, I'd suggest just lockstep mode if you wanted to go a bit beyond the normal Advanced ECC. Then you can do those 8GB x 12 modules, use lockstep mode, have 96GB of memory and run at 1333 Mhz.

 

Thank you for your reply, i will look into this.