1 Reply Latest reply: Jul 15, 2009 6:32 AM by 807557 RSS

    Renegotiate SCSI speed

    807557
      Hello forum.
      Due to a bad disk, seams that the bus SCSI is now somehow limited(several bus SCSI resets and so on...). I replaced the disk for a new one but the SCSI bus speed still is very low. How do I force the renegotiation of the SCSI bus speed? Unplugging and plugging the SCSI cable is not enough.

      Best regards,
      -ss-vcf
        • 1. Re: Renegotiate SCSI speed
          807557
          SCSI buses work fine at full speed until they hit a problem and then the scsi bus resets and comes back slower than before. It continues to do this until transmission problems disappear. The logic here is that buses running at high speed have more chance of collisions. So the bus resets itself and then drops the bus speed to avoid collisions, and does this until collisions disappear.

          So if you've replaced the disk and your still getting scsi bus resets then try;
          powering off the server and then pull all plugs from it for a few minutes this will completely reset the scsi bus.
          check all cables and re-seat them a bad
          Check termination and make sure termination is correct for the bus speed you require.

          Only disconect cables when the server is powered off, do not break the scsi bus while it's up and running.
          This will eventually fry the scsi card so only remove terminators and cables when the server's powered off.

          Also you could drop down to the ok prompt and do a probe-scsi-all and see if you can see any problems from there.