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SCSI controller card troubleshooting with Apple Macintosh

August 24th, 2009

SCSI Controller Card I just installed a new hard drive, but now get intermittent lock ups on boot, error messages that I cannot read from the hard drive, or errors that show problems with the hard drive or file system. What should I explore first?

Note: This document applies to Mac OS 8.6 thru 9.x.

Some operating systems do not support all default SCSI drive features. If you are using a generic (not MAC branded) hard drive, the drive may behave erratically as it may not be optimized for the operating system. If you are seeing these symptoms, find out if SCSI Mode Page editing is supported by the SCSI controller. Disable Initiate Synchronous Negotiation and Disconnect/Reconnect if available at the SCSI controller. Also Unit Attention. Run the Media Verify option from the SCSI controller utilities, to verify data integrity on the hard drive.

These features may not be available at all SCSI controllers. Third party software may be needed to set the hard drive SCSI Mode pages for these features. You will need a SCSI Mode Page Editor tool. See your system manufacturer for SCSI tools.

Isolate the suspect drive to the only device on the controller and retest. Replace the data cable, devices, or external terminators. Verify that both ends of the SCSI bus are terminated. If the hard drive has an option for Termination Power–use it. Or confirm that the SCSI controller supports/supplies bus Termination Power. This is especially important with long cable runs or when using more than one SCSI device.

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