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HP DL380 G7 - cache settings vmware

 
markussch
Occasional Visitor

HP DL380 G7 - cache settings vmware

Hello, I have checked an existing Raid configuration on an DL380G7 with a P410i smart controller. I coud se that on the controller are strange settings configured. (see attachment for the hpcucli export) . For example cache ratio : 100% write and 0% write. I think that is not a recomendet configuration for a server. Can someone give me some input for this configuration example?  I have a raid 5 with 4x 450GB SAS discs.

3 REPLIES
PGTRI
Honored Contributor

Re: HP DL380 G7 - cache settings vmware

hi,

 

So far i know, you'll need a battery attached to the controller to be able to change this settings.

 

Thanks

 

regards,

How to Say Thank You? Just click the KUDOS!
RbBsmn
Regular Advisor

Re: HP DL380 G7 - cache settings vmware

Hi,
I'm also quite sure you would need a battery.
Also your firmware is quite behind as the latest version is 6.60 and you are still using 5. 15 if I read it correctly (am using this website on my phone....).

However there is no fixed default setting that is ideal. It depends if your applications mostly do write operations or mostly read operations.

However a quite common setting I come across is 80% write and 20% read.
Did my post help? Thank me with kudo's! :)
lightman
Advisor

Re: HP DL380 G7 - cache settings vmware

Hello, using 0% Write cache in vmware will kill your performance.

you absolutely need write cache for vmware esx

 

if you don't have a BWCC battery, get one ASAP, in the mean time you can force enable write cache (in my case, i get a jump of 8X in performance using 25% read / 75% write with 2x RAID5 (8 drives).

 

keep in mind that force enable write cache is EXTREMELY DANGEROUS!, if your lost power, the information contained in the write cache will be TOTALLY LOST, and you will LOST DATA.

 

Here is a post about how to enable write cache:

http://alexlurthu.wordpress.com/2010/06/07/change-accelerator-cache-ratio/

 

from the hpacucli:

 

ctrl slot=0 modify nbwc=enable

ctrl slot=0 modify cacheratio=25/75

now check it with>

ctrl slot=0 show detail

 

it should say:

Cache status: OK

Accelerator ratio: 25% Read / 75% Write

No-Battery Write Cache: Enabled

 

if you also want to enable DRIVE write cache (not recommended as is even MORE dangerous)

ctrl slot=0 modify dwc=enable

 

I do it only for now because this is a test server, but once in production i will disable drive write cache.

 

also to check if array accelerator is activated for every logical drive:

 

ctrl slot=0 ld 1 show

ctrl slot=0 ld 2 show

and so on...

 

also it would be interesting to know what others think about enabling Drive Write Cache.

 

EDIT: removed a lot of detail, once I saw your jpg , you have already installed hpacucli :) sorry.