Probably because we qualified both. Dual-sourcing critical components like disk drives is standard procedure when multiple sources are available. (I can't say for sure because the qual for those happened before I got here.)

Doing so has saved the posterior anatomy of more than one system vendor when it turns out that the product delivered by one source suddenly develops problems due to manufacturing process changes that occurred after qualification and/or problems that take a long time to appear (anyone remember the IBM stiction problems :-), or availability simply becomes a problem.

I would imagine that most vendors don't want to qualify more than 2 both due to the cost of each qual and also because of the fact that qualifying N drives turns into an N^2 problem. If you qualify 3 drives, you have to ensure that all combinations work (e.g. a SCSI bus with drive A, B, and C works well, ditto for just drive A, B, and drive A, C, etc.).

You wouldn't think that this should be an issue but it has been in the past.

I think you can get away with skimping on some testing for situations where the N Gbytes and M Gbyte drives from the same manufacturer are the same family running the same firmware. But even then, I suspect you have to check for vibration issues in your supported enclosures.

Ray

-----Original Message----- From: Jonah Yokubaitis [mailto:barron@staff.texas.net] Sent: Thursday, March 11, 1999 7:18 PM To: Chen, Ray Cc: 'Jim Davis'; toasters@mathworks.com Subject: RE: FW: Shelves, disks, et al

On Thu, 11 Mar 1999, Chen, Ray wrote:

|The truly sad thing is that you are correct in that |most people won't buy Michael's argument but that |Michael is correct when he tries to communicate |how much work goes into disk drive qualification |and how painful the problems can be if you try |and put in joe-random-disk drive, even the same |model from the same vendor, and get unlucky. | |Heck, *I* didn't buy the argument until I spent |a few years at another company where I exposed to |some of what happens in drive qualification and |saw what could go wrong in the lab and in the field. | |To be safe, you really need the same vendor, same |drive, and exact same firmware and that's typically |very hard to get unless you buy from the system vendor |instead of the drive vendor. Even then, that's not |a guarantee that you won't get bit, your odds are |just better.

Ray,

If that's the case, then why does one of our F630s (9gig SCSI drives in it) having 2 *different* model numbers of drives in it? All drives came directly from Netapp.

Jonah

Jonah Barron Yokubaitis http://www.texas.net <--- The ISP http://www.giganews.com <--- News Outsourcing