DL380 G6 Memory configuration

[Wayne]

Hi

It looks like the memory extension of a 380 G6 server is a little adventure, also with the helpful DDR3 Memory Configuration Tool ;-)

So I hope some of you can help me with a few Questions.

We bought the server (491316-421) with 6 x 2GB Memory PC3-10600R (1333 MHz) already inside.

A few weeks later we extended the first time with 4 x 4GB Kingston KTH-PL310Q/4G Modules and too bad but they are only 1066 MHZ.

So we have now 28 GB, 6 x 2GB 1333 original HP and 4 x 4GB 1066 Kingston modules and so far they are working very well.

But now I wanna extend again and don't know what would be the best way.

Actual config:

Proc1 2D: 2GB
Proc1 3A: 4GB
Proc1 5E: 2GB
Proc1 6B: 4GB
Proc1 9C: 2GB
Proc2 2D: 2GB
Proc2 3A: 4GB
Proc2 5E: 2GB
Proc2 6B: 4GB
Proc2 9C: 2GB

1. Is it ok to mix 1333 and 1066 modules?
2. Would it be better to replace the 1066 and buy 1333 now to extend to totaly 48 GB for an ESX envronment or is it not that important?
3. Can I just put new memory to the empty slots or should I rearrange the existing memory so that the biggest would be first or the faster first?

Sorry, long description, but I'm not sure if the difference of the performance will be that big related to mixed modules from the size and the speed.

I'm grateful for any suggestion

Thx
Wayne

[Zygmunt Krawczyk]

1. Is it ok to mix 1333 and 1066 modules?
It is OK, but might be not optimal. Which processor model do you have?

2. Would it be better to replace the 1066 and buy 1333 now to extend to totaly 48 GB for an ESX envronment or is it not that important?
It depends on processor model.

3. Can I just put new memory to the empty slots or should I rearrange the existing memory so that the biggest would be first or the faster first?
At the first step you shoud add two 4GB modules, to have total of 6x2GB + 6x4GB.

[Wayne]

Hi and thx for the fast reply :)

It's a Intel® Xeon® X5550 (4 Cores, 2,66 GHz, 8 MB L3, 95 W) with 2 processors.

So I should buy the same 4GB modules KTH-PL310Q/4G also if they are just 1066 MHz?

Thx for your assistant, I'm going crazy with this memory population guidelines and requirements ;)

[Zygmunt Krawczyk · Accepted solution]

X5550 processors have 1333MHz memory interface, it can work in 1066MHz and 800MHz also. So the best solution is to have 1333MHz memory. For two processor system optimal memory setup is multiple of 6 memory modules.

So the best solution to get 48GB RAM is buying 6x8GB 1333MHz memory modules. I recommend HP memory modules - comparable price to 3rd party.

500662-B21 HP 8GB 2Rx4 PC3-10600R-9 Kit

[Wayne]

Now I'm more confused ;)

After thoroughly studying the quickspecs I found that 8GB will always run at 1067 MHz max.
So I can't run them all on 1333, right? I guess then I will keep the existing modules and not replace them.

Would it be ok to buy just 2 x 4GB and 3 x 8GB (HP 8GB 2Rx4 PC3-10600R-9) so finally I will have 60GB for my ESX?

[Zygmunt Krawczyk]

> After thoroughly studying the quickspecs I found that 8GB will always run at 1067 MHz max.
So I can't run them all on 1333, right?

It is true for 8GB PC3-8500 (DDR3-1066) memory modules (516423-B21). Using 8GB PC3-10600 (DDR3-1333) memory modules (500662-B21) the memory will run at 1333MHz for configuration up to two modules per memory channel.

> Would it be ok to buy just 2 x 4GB and 3 x 8GB (HP 8GB 2Rx4 PC3-10600R-9) so finally I will have 60GB for my ESX?

This setup will run at 800MHz, as you will have three modules per channel.

[Zygmunt Krawczyk]

Probably you are reading quick spec not up to date. Read the current:

http://h18000.www1.hp.com/products/quickspecs/13234_div/13234_div.HTML

[Wayne]

wow, ok, this document has really other informations than mine ;)

So, if they all run just at 800MHz, will that be a big permormance reduction or just slightly with 60GB?

Thank you very much for your help!

[Zygmunt Krawczyk]

Memory throughput at 800MHz is 40% lower than at 1333MHz.
Additionaly your 60GB setup is imbalanced betweent processors
and memory channels. I can't predict performance reduction in ESX,
but I'm sure that reduction will be high.

[Michael A. McKenney]

Most likely it will cause issues. I would consider getting matching ram. The slowest RAM will set the channel speed. The speed mismatch could cause instability. This is probably the worst thing you could do on a file server.

[Wayne]

Ok, I guess I've got it, thank you both!

I will replace then all 2GB modules with the 8GB, because I will keep the 4 x 4GB I already have.
So finally I will have 6 x 4GB (1067) and 3 x 8GB (1333) and that will be the cheapest way to reach 48GB with just 2 modules per channel and so they will run at 1067 MHz.