Scsi-2 instead of scsi-3 problem

[guimaraes]

Hello,

Server specs:
- 6 compaq BF01863644 drives (scsi-3 U160, 15k, 18.2 GB)
- LSI logic megaraid 320-2x raid controller (U320, dual channel)
- chenbro rm311 backplane (U320)

Now the problem is, that my controller recognizes the disks as scsi-2, while they are scsi-3. This gives some real performance problems. Why does it recognizes the disks as scsi-2? Do i have to update the firmware?

[raadek]

Hi there,

Bear in mind that HP/Compaq hard drives have specific firmware which make them working properly with HP/Compaq controllers.

Hence you could have all sorts of issues when connecting a Compaq drive to a non-Compaq card or vice versa.

[guimaraes]

Yeah i thought so. These drives come from my older Compaq storageworks 4354R enclosure.

Do you know if i can update the firmware of these disks? I know they are actually seagate disks, but i can't find any seagate part nr. If i know that, i could ask the original firmware from seagate.

[raadek]

I am not sure if this is possible at all (firmware changes on a HDD) - at least I've never heard of it!

[guimaraes]

Yes it's possible :)
But do you maybe know, how i can find out which seagate drive it actually is?

[raadek]

One could guess it is either ST318452LC or ST318451LC, because the spec matches.

However... I am not sure if e.g. they were not tailor-made for Compaq (hence there would be no bog-standard firmware)

[guimaraes]

I contacted seagate, and this is their reply:

Mr.

Unfortunately, this/these drives came from an OEM, meaning our firmware
will not work for you. Updating with our firmware would kill the drive.
When Seagate manufactures drives for OEM's, these drives are designed to
their custom specifications. These design changes can cause the drive to
operate differently than general release drives. Since our OEM customers
consider these design changes proprietary information, Seagate has no
information or end user support available on these drives.

Please contact the manufacturer for further support.

Regards,

Rudy R.
Seagate Technical Support

[kris rombauts · Accepted solution]

Hello guimaraes,

the capabilities of the drive dictate if the SCSI ANSI version is set, and that
has to be set to SCSI-2 for backwards compatibility onto older controllers.
The indication of SCSI-2 does not mean the drive is Ultra-2 at all, it can be
aswell Ultra or Ultra3. Their is a difference in a disk being compliant to the
standard "ANSI SCSI-2" and it's speed which can be Ultra, Ultra-2 and Ultra-3, don't mix those two terms.

Some controllers use the ANSI SCSI information and some don't, the SCSI-2
indication is telling us what SCSI command set features this disk supports, not the speed.


The SCSI inquiry details in this case shows SCSI-II but this is often done for backward compatibility because those disk are also supported on ultra/ultra-II and ultra-III controllers.


If you really have performance problems you can measure, then it is not due to this.
Only a SCSI analyser trace will prove you at what exact speed the disks negotiate with the controller.


HTH

Kris

[guimaraes]

Kris,
(I see you are from Belgium, do you speak Dutch? Can i contact you by e-mail or MSN? Maybe that's easier to communicate because i'm Dutch.)

The weird thing is, everything is Ultra 3 and Ultra 4. There is no Ultra 3 device or cable in the system. And the controller is a brand new LSI logic megaraid 320-2x!

Also, i don't see ANSI mentioned anywhere in the BIOS.

DO you know a good scsi analyser for linux? I run centos 4.3

Thanks!

[kris rombauts]

guimares,

their is no ANSI setting in the BIOS whatsoever, as part of a SCSI enquiry the drive reports just that one of it's capabilities or features is that it's SCSI-II compliant and that by itself is hardcoded by the disk manufacturer or OEM in the firmware of the disk controllerboard, it cannot/should not be changed.

If the disk you have is a Ultra160 then it will/should perform at that speed/performance if the controller is the same spec or higher and the backplane/cable
is appropriate spec'ed.

Their are many factors that play a role when dealing with performance issues (H/W config/OS driver/file system tuning/ application, but the one questioned above should now be cleared up.

When putting toggether components that are not tested/certifed all together by a vendor, it is always possible you hit a limitation , incompatibility/bug or a different interpretation of a standard that causes the whole not to work/perform as one expects. Depends what you experience as the performance problem (is it measured and how ?) but i don't want to go further into researching/discussing this as it goes beyond the scope of this forum :-)


Sorry , don't know of a software based SCSI analyser for Linux.


Kris