Areca ARC-8050T3U 6-Bay Thunder3 Desktop RAID Storage Array - Manual (Page 151)

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APPENDIX
In the normal status, the newly installed drive will be recon-
figured an online free disk. But, the newly-installed drive is
automatically assigned as a hot spare if any hot spare disk
was used to rebuild and without new installed drive replaced
it. In this condition, the Auto Declare Hot-Spare status will be
disappeared if the RAID storage has since powered off/on.
The Hot-Swap function can be used to rebuild disk drives in
arrays with data redundancy such as RAID level 1, 1E, 3, 5, 6,
10, 30, 50 and 60.
• Auto Rebuilding
If a hot spare is available, the rebuild starts automatically
when a drive fails. The RAID controllers automatically and
transparently rebuild failed drives in the background at user-
definable rebuild rates. If a hot spare is not available, the
failed disk drive must be replaced with a new disk drive so
that the data on the failed drive can be automatically rebuilt
and so that fault tolerance can be maintained.
RAID controllers will automatically restart the system and
rebuilding process if the system is shut down or powered off
abnormally during a reconstruction procedure condition. When
a disk is hot swapped, although the system is functionally
operational, the system may no longer be fault tolerant. Fault
tolerance will be lost until the removed drive is replaced and
the rebuild operation is completed.
During the automatic rebuild process, system activity will con-
tinue as normal, however, the system performance and fault
tolerance will be affected.
• Adjustable Rebuild Priority
Rebuilding a degraded volume incurs a load on the RAID stor-
age. The RAID controllers allow the user to select the rebuild
priority to balance volume access and rebuild tasks appropri-
ately. The Background Task Priority is a relative indication of
how much time the controller devotes to a background opera-
tion, such as rebuilding or migrating.