Proware EP-3164D-GAS3, User Manual

Page: 96 / 160

iSCSI GbE to SAS/SATA II RAID Subsystem
96 User Manual
Chapter 6 Advanced Operations
6.1 Volume Rebuild
If one physical disk from a RG, which is set to a protected RAID level (e.g. RAID 3,
RAID 5, or RAID 6), failed or has been unplugged/removed, the status of RG is
changed to degraded mode. The system will search/detect spare disk to rebuild
the
degraded RG to become normal/complete. It will detect dedicated spare disk as rebuild
disk first, then global spare disk.
The iSCSI RAID subsystem supports Auto-Rebuild. The following is the scenario:
Take RAID 6 for example:
1. When there is no global spare disk or dedicated spare disk in the system,
controller will be in degraded mode and wait until (A) there is one disk
assigned as spare disk, or (B) the failed disk is removed and replaced with
new clean disk, then the Auto-Rebuild starts. The new disk will be a spare disk
to the original RG automatically.
If the new added disk is not clean (with other RG information), it would be
marked as RS (reserved) and the system will not start "auto-rebuild".
If this disk is not belonging to any existing RG, it would be FR (Free) disk and
the system will start Auto-Rebuild.
If user only removes the failed disk and plugs the same failed disk in the same
slot again, the auto-rebuild will start running. But rebuilding in the same failed
disk may impact customer data if the status of disk is unstable. It is
recommended for users not to rebuild in the failed disk for better data
protection.
2. When there is enough global spare disk(s) or dedicated spare disk(s) for the
degraded array, the system starts Auto-Rebuild immediately. And in RAID 6, if
another disk failure occurs during rebuilding, the system will start the above
Auto-Rebuild process as well. Auto-Rebuild feature only works when the status
of RG is
"Online" . It will not work at “Offline” status. Thus, it will not conflict
with the “Roaming” .
3. In degraded mode, the status of RG is “Degraded” . When rebuilding, the
status of RG/VD will be “Rebuild” , the column “R%” in VD will display the
ratio in percentage. After completing the rebuilding process, the status will
become “Online”. RG will become complete or normal.