The 3ware RAID controller was unable to complete a rebuild operation. This error can be caused by drive errors on either the source or the destination of the rebuild. However, due to ATA drives’ ability to reallocate sectors on write errors, the rebuild failure is most likely caused by the source drive of the rebuild detecting some sort of read error. The default operation of the 3ware RAID controller is to abort a rebuild if an error is encountered. If it is desired to continue on error, you can set the Continue on Source Error During Rebuild policy for the unit on the Controller Settings page in 3DM.