Troubleshooting guide

Using the Storage Subsystem 7-23
Compaq Confidential – Need to Know Required
Writer: Robert Young Project: Compaq AlphaServer DS20E System Comments:
Part Number: ER-K8F6W-UA .A01 File Name: h-ch7 Using the Storage Subsystem.doc Last Saved On: 10/4/99 11:13 AM
External SCSI Expansion
External SCSI devices, such as tabletop or rackmounted storage devices, can
be connected to the system using PCI-based SCSI adapters. Use the following
rules to determine if a particular device can be used:
■ The device must be supported by the operating system. Consult the
software product description for the device or contact the hardware
vendor.
■ A maximum of seven devices can be attached on any one SCSI
controller.
■ Each device on the bus must have a unique SCSI ID. You may need to
change a device’s default SCSI ID in order to make it unique. For
information about setting a device’s ID, refer to the guide for that
device.
■ The entire SCSI bus length, from terminator to terminator, must not
exceed 6 meters for fast-differential connection to SCSI, or 3 meters for
fast single-ended connection.
■ Ensure that the SCSI bus is properly terminated and that no devices in
the middle of the bus are terminated.
■ For best performance, wide devices should be operated in wide SCSI
mode.