Dell SAS5 Performance Issue

[Richard Tector]

Matthew Jacob wrote:
> It's been seen before but the fix isn't know yet.
>
> On 3/27/07, Richard Tector <richardtector at thekeelecentre.com> wrote:
>> I'm suffering from very slow write performance on a Dell PowerEdge 860
>> with the SAS5/IR controller (mpt driver) running either 6.2-RELEASE or
>> 6.2-STABLE with sources from yesterday. The controller hosts 2 Western
>> Digital 320GB SATA disks in a RAID1 configuration.
>> Reads approach 65MB/s however writes appear extremely slow, in the
>> region of 6-7MB/s with a dd and a blocksize of 1MB all the way down to
>> about 300KB/s while extracting a ports snapshot.
>>
>> It was suggested to me that perhaps write caching has been disabled on
>> the controller however no options exist within the BIOS configuration to
>> view/adjust *any* caching options.
>>
>> Has anyone else experienced this issue? If so how did they resolve it?
>> Also, is there any way to toggle the caching settings from FreeBSD?
>>
>> Regards,
>>
>> Richard Tector
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Thank you for the quick reply.
Is there any information I could obtain that would be of use to you in 
tracking this one down?

Regards,

Richard