Calculating the true SCSI Bus Length


To accurately calculate the total SCSI BUS length of your storage configuration, add to the physical SCSI cable(s) length being used, 2 feet for each storage drive, and 2 feet for each library controller in the BUS chain.


Example - Single Library with two (2) 5.2 GB drives:


2 drives + 1 controller x 2 ft = 6 ft of internal resistance


6 ft (internal resistance) + 3 ft (SCSI cable) = 9 ft Total Bus length.


Note: This is within the SCSI Specification for this particular device.


In some configurations you will find that the total BUS length exceeds the maximum allowed under the single-ended Host adapter specification for that device. This is especially true when connecting to libraries with 5.2 GB storage drives or higher, or libraries with a higher number of storage drives (5 to 10).


We strongly recommend that library configurations that are at or that exceed their SCSI specification use a differential SCSI Host adapter card. This will insure that the proper "signal" strength necessary to ensure reliable communication on the BUS to the storage device is provided for.