SS20 not recognizing IBM hard drives

Posted by: admin  :  Category: Hardware

It was not very obvious and took me quiet some time to find out why two recently acquired Sun SS20 machines did not recognize IBM SCA hard drives.

Both machines originally came with very old 1 GB SCA hard drives. Thus is why I wanted to replace them by bigger 4 GB IBM hard drives (DDRS-34560).

Unfortunately Sun’s OpenBoot firmware would not recognize my replacement drives.

Since the drives were spinning up, I could not believe that the drives had failed. Testing in another machine showed me I was right: the drives were just running fine.

So why would they fail in the SS20’s?

After some research I found that the SS20 scsi bus supports wide and narrow SCSI-2, though only in single ended mode.

Since my IBM drives have not had the jumper #6 (S/E mode) closed, they did not initialize properly on the bus. After closing the jumper the drives were also recognized on the SS20’s.

One Response to “SS20 not recognizing IBM hard drives”

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