Dell SAS5 Performance Issue

[Tom Judge]

Richard Tector wrote:
> Ivan Voras wrote:
>> Richard Tector 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.
>>>     
>>
>> You looked in the controller's BIOS, not motherboard's, right?
> Indeed I did.
>> There should be at least a "write through" vs "write back" switch...
> Correct, there should be options, but there aren't. The controller BIOS 
> has very few options at all in fact.
> 
>> No, but can you post the relevant bits for the controller from dmesg?
>>   
> Sure:
> 
> mpt0: <LSILogic SAS/SATA Adapter> port 0xec00-0xecff mem 
> 0xfe9fc000-0xfe9fffff,0xfe9e0000-0xfe9effff irq 16 at device 8.0 on pci2
> mpt0: [GIANT-LOCKED]
> mpt0: MPI Version=1.5.12.0
> mpt0: mpt_cam_event: 0x16
> mpt0: Unhandled Event Notify Frame. Event 0x16 (ACK not required).
> mpt0: mpt_cam_event: 0x12
> mpt0: Unhandled Event Notify Frame. Event 0x12 (ACK not required).
> mpt0: mpt_cam_event: 0x12
> mpt0: Unhandled Event Notify Frame. Event 0x12 (ACK not required).
> mpt0: mpt_cam_event: 0x16
> mpt0: Unhandled Event Notify Frame. Event 0x16 (ACK not required).
> [...snip...]
> da0 at mpt0 bus 0 target 0 lun 0
> da0: <Dell VIRTUAL DISK 1028> Fixed Direct Access SCSI-5 device
> da0: 300.000MB/s transfers, Tagged Queueing Enabled
> da0: 305175MB (624998400 512 byte sectors: 255H 63S/T 38904C)

I have just stumbled across this problem on 4 PE860's and 2 PE840's.  I 
have been through the BIOS of the card and found no information about 
caching in any of the menus.  I then decided to take the card out and 
could not see any place to attach a cache battery backup unit,  I could 
also not see any ram chips on the card.

Is there any news on the performance of this card?

Tom