topic Re: Cache on Smart Array 5i plus in ProLiant Servers (ML,DL,SL)

Cache on Smart Array 5i plus

Anna Cheng — Thu, 15 Jan 2009 07:10:42 GMT

I am looking into the write performance and have a few questions on the cache. Hope someone may know the answer.

a. for the smart Array 5i Plus controller, and without BBWC, will there be any cache or memory on the controller?

b. I assume the answer for (a) is no. If so, how can we find out what is the allocation for read/write? will it be 50% for read and 50% for write? can it be changed?

thanks

Re: Cache on Smart Array 5i plus

Vulcan Maximus — Thu, 15 Jan 2009 13:50:06 GMT

Hi Anna,

Following are the answers for your queries.

A. smart Array 5i Plus controller has
64mb onboard memory(apart from the memory that you add on.)

B.To see the performance Read and Write.YOu could use Array configuration utility, Highlight the controller, then Use controller properties or statistics on the right hand side.A new window appears.Which would show you all the details.

Following are Features of Smartarray 5i Plus:
*********************************************
Key Products Features
*********************
Smart Array 5i Plus
Increased performance over the Integrated Smart Array Controller and the Smart Array 5i Controller.
Transportable, hardware-based Wide Ultra3 SCSI RAID controller, with 64MB of memory.
More robust and easier to use than software-based RAID.

Try and let us know.

Re: Cache on Smart Array 5i plus

gregersenj — Thu, 15 Jan 2009 14:46:59 GMT

Without BBWC, the cache is use for read cache only = 100% used for read cache.

With BBWC the cache is use for read and write cache.
If i remember correctly default is 50 / 50%

You can see and change that using the ACU

Cheers
/jag

Re: Cache on Smart Array 5i plus

Anna Cheng — Thu, 15 Jan 2009 16:04:52 GMT

thank you both.

gregersenj,
does it mean that it is the *same* 64MB cache, but when I included BBWC, then the cache will become writable?

Re: Cache on Smart Array 5i plus

Greybeard — Thu, 15 Jan 2009 17:23:15 GMT

Correct, at the default of 50%/50% the 64MB would become 32MB read cache and 32MB write cache. The batteries are there in case the server loses power and data has arrived in cache but has not been written to disk yet, then when power is restored to the server the controller will complete the write operation to disk, so no battery = loss of unwritten data.

Re: Cache on Smart Array 5i plus

Anna Cheng — Fri, 16 Jan 2009 07:25:41 GMT

thank you all