APC RAID Subsystem SCSI-SATA II - Manual (Page 7)

- 7 -
RAID width,
RAID copy,
RAID row
(RAID cell in
one row)
RAID width, copy and row are used to describe one VG.
E.g.:
1. One 4-disk RAID 0 volume: RAID width= 4; RAID
copy=1; RAID row=1.
2. One 3-way mirroring volume: RAID width=1; RAID
copy=3; RAID row=1.
3. One RAID 10 volume over 3 4-disk RAID 1 volume:
RAID width=1; RAID copy=4; RAID row=3.
WT Write-Through cache write policy. A caching technique in
which the completion of a write request is not signaled until
data is safely stored on non-volatile media. Each data is
synchronized in both data cache and the accessed physical
disks.
WB Write-Back cache write policy. A caching technique in which
the completion of a write request is signaled as soon as the
data is in cache and actual writing to non-volatile media
occurs at a later time. It speeds up system write performance
but needs to bear the risk where data may be inconsistent
between data cache and the physical disks in one short time
interval.
RO Set the volume to be Read-Only.
DS Dedicated Spare disks. The spare disks are only used by one
specific VG. Others could not use these dedicated spare disks
for any rebuilding purpose.
GS
Global Spare disks. GS is shared for rebuilding purpose. If
some VGs need to use the global spare disks for rebuilding,
they could get the spare disks out from the common spare
disks pool for such requirement.
DC Dedicated Cache.
GC Global Cache.
DG DeGraded mode. Not all of the array’s member disks are
functioning, but the array is able to respond to application
read and write requests to its virtual disks.
S.M.A.R.T. Self-Monitoring Analysis and Reporting Technology.