Re: Integrated perc 5/i

Yay - looking forward to your results!

- Luke

On 8/16/07 3:14 PM, "Merlin Moncure" <mmoncure(at)gmail(dot)com> wrote:

> On 8/16/07, Luke Lonergan <llonergan(at)greenplum(dot)com> wrote:
>>
>> Hi Michael,
>>
>> There is a problem with some Dell "perc 5" RAID cards, specifically we've
>> had this problem with the 2950 as of 6 months ago ­ they do not support
>> RAID10. They have a setting that sounds like RAID10, but it actually
>> implements spanning of mirrors. This means that you will not get more than
>> one disk worth of performance whether you are performing random seeks
>> (within a one disk sized area) or sequential transfers.
>>
>> I recommend you read the section in the Dell configuration guide very
>> carefully and look for supplemental sources of technical information about
>> it. We found the issue clearly explained in a Dell technical memo that I
>> don't have in front of me ­ we were shocked to find this out.
>
> interesting. this may also be true of the other 'rebrands' of the lsi
> logic chipset. for example, the ibm 8480/exp3000 sets up the same
> way, namely you do the 'spanadd' function of the firmware which layers
> the raids.
>
> fwiw, I will be testing perc 5 raid 10, 01, 00, and 05 in a dual
> controller controller configuration as well as dual controller
> configuration over the md1000 (which is active/active) in a few days.
> This should give very good support to your claim if the arrays spanned
> in software singnificantly outperform a single controller.
>
> merlin