Date - 01/2007
Affected Product & Version - Netvault Backup v7.4.x
Affected Module & Version - N/A
OS Version - N/A
Application Information - N/A
Why is it recommended that tape devices should not be connected to RAID controllers?
f a slow speed bus device (that is, tape device), is connected to a high-speed, RAID bus controller, the result will be anything from,
intermittent tape hardware errors such as "bad data" and "Cyclic Redundancy Check" (CRC) errors to "unable to space to end of data" errors and complete SCSI bus locks or resets.
A bus reset may require a restart to get the tape device functionality returned to the system.
RAID controllers are capable of controlling multiple disk drives and they are, by nature, in a constant state of activity.
This perpetual activity causes the tape device to "get lost" on the bus. In addition, RAID controllers are high speed, wide buses which have trouble communicating accurately with low speed, narrow bus devices such as tape devices, unless termination is very carefully done. Even under the circumstance of proper termination, the above-mentioned errors will prevent reliable and successful device operations.
For the reasons stated above, most controller manufacturers recommend that tape hardware not be placed on the same SCSI bus as the local hard drives, and that drive arrays should not share a RAID controller with tape hardware. Always consult the controller card manufacturer's recommendations when troubleshooting or planning a tape hardware configuration.