A four-way cluster is attached to two fabrics. Each member has two HBAs connected to each fabric. Each fabric has two subsystem connections. Each cluster member is a primary for one application. All LUNs appear on all storage ports with workload equally distributed across all. Each host has two dedicated HBAs for tape that can each see four independent LTO II (35MB/s) tape drives. All files are large and involve sequential I/O. Performance reporting shows a large read pending at the host during multi-threaded backup. What is the most probably cause for the large read pending at the host?

A.
native command queuing

B.
SCSI Queue Depth too high

C.
SCSI Queue Depth too low

D.
throttling threshold is too high