USB 3.0-to-SATA II RAID Subsystem
User’s Manual
15
1.4 RAID Modes
Normal Mode
Normal mode means all of the configured hard drives exist and in good condition and the
RAID controller is not in rebuild condition.
Degrade Mode
In degrade mode, some hard disk in RAID is removed or defective. No other RAID drive is
under rebuilding condition. The firmware or application will so some process to warn users
the need to replace the defective hard disk with a healthy one.
Rebuild Mode
Rebuild mode means a RAID drive is doing data recovery. Only when host controller does
not access RAID hard disks, the RAID controller will resume rebuild mechanism. Rebuild will
be paused any time when host controller is executing commands.
Only a defective hard drive will be rebuilt each time. For example, if more than one hard
disk is defective in RAID 10/Clone mode, a defective hard drive will be rebuilt only after the
previous defective one is rebuilt successfully.
Broken Mode
Broken mode means the number of hard disk is not enough to keep RAID run normally.
RAID hard disks then will just keep some basic communication functions with application.
No other data access is allowed.
If broken mode is caused by RAID hard disk defect, the RAID drive will crash. However, if
the broken mode is caused by just removing some hard disks and those removed hard
disks’ data remain unchanged, the RAID controller will enter normal mode or degrade mode
when the hard disks are connected to the RAID controller again.
On-line Hot Spare
Spare hard disks which have not been used initially by the RAID controller can be accessed
when the RAID controller needs more hard disks afterward.
The RAID controller uses spare hard disks in auto mode, where the initially un-used hard
disks will just stand by. When needed, the RAID controller will use these hard disks
automatically.
