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Chapter 4 Advanced operation
4.1 Rebuild
If one physical disk of the VG which is set as protected RAID level (e.g.: RAID
3, RAID 5, or RAID 6) is FAILED or has been unplugged/removed, then the
status of VG is changed to degraded mode, the system will search/detect
spare disk to rebuild
the degraded VG to a complete one. It will detect
dedicated spare disk as rebuild disk first, then global spare disk.
Netstor iSCSI series
controllers support 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 VG automatically.
If the new added disk is not clean (with other VG 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 VG, 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.
Netstor
suggests all customers 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, controller starts Auto-Rebuild immediately.
Moreover, in RAID 6, if there is another disk failure occurs during