SUMMARY: SCSI rewritable optical disk drive

Date: Mon Aug 23 1993 - 17:16:37 CDT

Here's my summary from several users regarding the following problem:
Apparently my SCSI cable is too long...

>I had an interesting problem occur when trying to install a
>SCSI rewritable optical disk drive. I installed the software
>and rebuilt the kernel all to factory specs and was then going to
>boot with the new kernel after plugging in the disk drive. I powered
>down the machine (Sun Sparc 10 model 30) and attached the CD-ROM into
>the SCSI port and then attached the disk drive to the CD-ROM. When
>I rebooted, I got the following error message and then the machine
>just hung:
> esp0: SCSI bus DATA IN phase parity error
>My first guess is that the cable connecting the optical drive to
>the CD-ROM is too long (about 15 feet) in other ideas? By the
>way, the rewritable optical drive is internally terminated.

From: Mike Raffety <>

DEFINITELY too long ... the fast SCSI bus on the SS-10 is effectively limited to about six meters, and you've got five in that cable alone.

---- From: "Michael R. Zika" <>

This is probably your problem. The SS-10's require "active" termination -- all the internal terminators I've ever heard of are "passive" terminators. The terminator we use (from Sun) is part no. 150-1785-02. Available through SunExpress, or you could try the myriad of third party vendors...

---- From: (Russ Poffenberger)

Yes, this is much too long for a SCSI-2 bus. If you had the very best cables, and forced perfect termination, maybe you could get away with it. You also need to count internl cabling in the CDROM and optical drive enclosures. This will make the total even longer.

---- From: robert@hemingway.weitek.COM (Robert Plamondon)

You've already guessed the first things I'd check. I'd open up the drive to be SURE it's terminated. Also, presumably, the CD-ROM used to be terminated. Are the terminators gone now? They should be. Also, I've heard of lots of people having trouble with long SCSI cables. Personally, I've had some trouble just with bad connections: removing the cable and putting it back in more squarely seemed to fix some problems.

---- From: (Andy Finkenstadt)

Use ACTIVE TERMINATION, or shorten the cable.

---- From: (Kevin Sheehan {Consulting Poster Child})

15 feet is way too long. 6 inches is more like the go.

Thanks Sun-men and Sun-women,


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