Qsan Technology P300H61, User Manual

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VD V irtual D isk. Each RD could be divided into several VDs. The VDs
from one RG have the same RAID level, but may have different
volume capacity.
LUN L ogical U nit N umber. A logical unit number (LUN) is a unique
identifier which enables it to differentiate among separate
devices (each one is a logical unit).
GUI G raphic U ser I nterface.
RAID cell When creating a RAID group with a compound RAID level, such as 10,
30, 50 and 60, this field indicates the number of subgroups in the RAID
group. For example, 8 disks can be grouped into a RAID group of RAID
10 with 2 cells, 4 cells. In the 2-cell case, PD {0, 1, 2, 3} forms one RAID
1 subgroup and PD {4, 5, 6, 7} forms another RAID 1 subgroup. In the 4-
cells, the 4 subgroups are PD {0, 1}, PD {2, 3}, PD {4, 5} and PD {6,7}.
WT W rite- T hrough cache-write policy. A caching technique in which
the completion of a write request is not signaled until data is
safely stored in non-volatile media. Each data is synchronized in
both data cache and accessed physical disks.
WB W rite- B ack 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 R ead- O nly.
DS D edicated S pare disks. The spare disks are only used by one
specific RG. Others could not use these dedicated spare disks for
any rebuilding purpose.
GS G lobal S pare disks. GS is shared for rebuilding purpose. If some
RGs 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.
DG D e G raded 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.
SCSI S mall C omputer S ystems I nterface.
SAS S erial A ttached S CSI.