After replacing a hot-swappable hard drive in a RAID 5 array, a technician notices decreased...

After replacing a hot-swappable hard drive in a RAID 5 array, the array must rebuild the data onto the new drive. This process involves reading data from the remaining drives and writing it to the new drive to restore full redundancy. The performance decrease is due to the intensive read and write operations necessary to rebuild the RAID array, which can take several hours depending on the size of the drives and the amount of data.