esxi 4 slow performance with p410 BBWC

[WGschwendtner]

Hi,

I've got slow disk performance on guests (3 W2k8, 64bit)

Hardware:

HP ML350G6, 24GB RAM, 2QC, P410 raid controller with 512MB BBWC, 1 LUN, RAID5 with 13x146GB 10k disks.

1x P212 with LTO3 attached and passthrou to W2k8 guest.

Is there anything wrong in LUN/RAID configuration? I tried spotlight for Windows and realizied no RAM cache activity. IOMeter with file server pattern shows a disk performance of 35MB/s at the beginning. It slows down to 5MB/s.

Any hints?

Thanks

Walter

[jsbarber]

Hi,

Have you enabled Write Back on the RAID ctrlr? If you're not seeing any cache usage, I'd be looking there first.

Also maybe check that the battery is charging properly. Most controllers will default to write through if bad BBU.

JB

[J1mbo]

The performance rate tends to suggest the array is operating with a write-through caching policy. Perhaps check in the P410 BIOS whether that is the case, confirm the battery operation (should be reported through vCentre) and if that is the case and the battery is OK, switch it to write-back.

However with 13 disks you'd be well advised to run this as a RAID-50 with 12 drives plus one spare IMO.

Please award points to any useful answer.

[dennes · Accepted solution]

With the latest Smart Arrays you have to manually enable write-back caching through the ACU (Array config util), which you can run from the SmartStart CD/DVD. You cannot do this from withing the BIOS app.

[WGschwendtner]

Thanks to all,

at the weekend I'm able to check this out.

I'll rate you as soon as possible.

Thanks for your answer

Walter

[fbroussey]

Hi Walter,

We are encountering the same issue with the same hardware. Have you solved the problem? Does the ACU allow you to modify the write cache parameter?

Thanks for your answer.

regards,

Frédéric

[WGschwendtner]

Hi Frederic,

yes, ACU let's you modify (enable/disable) write-back caching.

Performance didn't increase very much. I think I should do a redesign of this

disk array.

Thanks for all your answers.

Br Walter

[jsbarber]

Thank you for your email.

Unfortunately, I am out of the Office now until Friday 25th June. If your enquiry is urgent then please contact Support on +44 1246 457170 or alternatively at support@chatsworth.co.uk.

Regards,

John Barber

Senior Engineer

Chatsworth Computers