At power-on initialization time, or during a rescan, the 3ware RAID controller performs a “rollcall” of all drives attached to the card. After detection of the drives, the 3ware RAID controller then uses an internal algorithm to logically connect drives that belong to the same unit. If after rollcall a member of a unit is not found, the INCOMPLETE UNIT message
is sent. Examples of incomplete units are as follows:
Replacing the missing or dead drive and initiating a rebuild will change the state of the unit from an incomplete unit to OK. No rebuild is required if you replace the missing drive before loading the driver.