Having created ATA RAID back in 1997 we (Promise) know a lot about rebuilding arrays under various conditions. The RAID Engine is designed to set the rebuild speed at a low-medium priority in order maintain decent performance while the array or volume is being accessed during rebuild. Rebuilds can take anywhere from a few hours to 24 hours:
750GB 18 hours
1TB Disk 24 hours
*All Rebuild times are approx and can vary depending on system activity and disk performance.
If your rebuild is exceeding the times list above:
-Make sure the Disk is on our AVL (Approved Vendors List). We are very serious about the AVL when it comes to Drives as we must approve the Hardware and the Firmware of the Drive.
-The Disk (being rebuilt – the replacement Disk) could be “unhealthy” and suffering from numerous bad sectors which results in the Disk attempting to recover the bad sectors. If you are using Enterprise Class or RAID Edition Drives that feature Time Limited Error Recovery, this recovery process will be kept to a minimum of less than 10 seconds per bad sector. Non Enterprise Class Drives can take minutes during recovery and could slow the rebuild process significantly.