Which of the following explains why a backup tape drive might be “shoe-shining” during a backup?
A.
Read-after-write verification is being used to guarantee data integrity
B.
Data compression is rewriting the data to save space
C.
The tape head is dirty and needs to be cleaned
D.
The backup client is not providing data fast enough
Should be D; data compression rewriting the data to save space have nothing to do with the “shoe shinning” effect:
“A disadvantageous effect termed “shoe-shining” occurs during read/write if the data transfer rate falls below the minimum threshold at which the tape drive heads were designed to transfer data to or from a continuously running tape. In this situation, the modern fast-running tape drive is unable to stop the tape instantly. Instead, the drive must decelerate and stop the tape, rewind it a short distance, restart it, position back to the point at which streaming stopped and then resume the operation. If the condition repeats, the resulting back-and-forth tape motion resembles that of shining shoes with a cloth. Shoe-shining decreases the attainable data transfer rate, drive and tape life, and tape capacity.” –
http://en.wikipedia.org/wiki/Tape_drive#Technical_problems
The answer is definitely D because B has nothing to do with “shoe-shining” like BigTonka said.