topic Adding cache memory to the raid. in ProLiant Servers (ML,DL,SL)

Adding cache memory to the raid.

MaximNasonov — Mon, 27 Sep 2010 08:59:38 GMT

Hello,

We have a DL385 G7 CTO (573123-B21). It has integrated raid-controller P410i with Zero Memory Cache. So we cannot configure more than 2 logical drives. I think we need to buy 256 MB Cache Module (462968-B21). But I don't know about "Battery Kit upgrade" (462969-B21) (there are note: To enable BBWC on the 256MB cache). We need no RAID 5, just additional RAID 1.

Best regards,

Maxim Nasonov

Re: Adding cache memory to the raid.

elegant-it — Mon, 27 Sep 2010 11:25:46 GMT

The part number 462969-B21 is the battery kit to go along with the RAID upgrade, which allows you to enable the write cache in confidence (without this you get error messages warning of data loss should power failure occur).

I think you can also buy them together (256Mb and Battery) with one part number, but I don't have that information to hand at the moment.

Re: Adding cache memory to the raid.

MaximNasonov — Mon, 27 Sep 2010 13:03:46 GMT

I wonder what's cache's role in adding third logical drive. I need it only once. So can I go without the battery?

Re: Adding cache memory to the raid.

elegant-it — Mon, 27 Sep 2010 15:46:09 GMT

You dont need the battery part, but you wont/shouldnt turn on write caching without it, so you will not be achieving all of the benefits of the RAID card. If you are not bothered about the ultimate performance, don't worry about it.

Re: Adding cache memory to the raid.

afurman — Tue, 28 Sep 2010 19:12:40 GMT

Just try to switch off write cache on your workstation's HDD for an hour and you will instantly see the role it plays in any system.

What about adding the third logical drive. I do not think it depends on write cache memory presence in the RAID controller, but HP could make such a restriction in RAID's BIOS intentionally (if did) to point customers at the performance issues when their systems started growing.