Which of these identifies problems that can occur with RAID configurations?

The correct answer identifies a specific issue that can arise during the process of maintaining a RAID array. When a RAID array undergoes failure or when a drive is replaced, the rebuilding process often leads to performance degradation. During this time, the system is working hard to reconstruct the data across the drives, which can slow down read and write speeds, as the workload increases and resources are taxed more heavily. This is particularly noticeable in certain RAID levels, like RAID 5 or RAID 6, where data is striped and additional computations are necessary to rebuild lost information.

Conversely, the other choices do not accurately represent potential problems associated with RAID configurations. A complete data backup is a best practice and not a problem; performance improvement is often a benefit of using RAID rather than an issue; and maintenance-free operation is a misconception, as RAID systems do require regular monitoring and occasionally manual intervention for optimal performance and to address potential problems.