Hitachi Unified Storage VM, Product Overview Manual

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C A K D E F G H I J L M N O P Q R S T U V W X Y # B Z
A B C D F H J K L M P R S V
Hitachi Unified Storage VM Product Overview Guide
Glossary–4
copy of the original data. The copy operations can be synchronous or
asynchronous, and the pair volumes can be located in the same storage
system (in-system replication) or in different storage systems (remote
replication).
pair status
Indicates the condition of a copy pair. A pair must have a specific status
for specific operations. When an operation completes, the status of the
pair changes to the new status.
PDB
power distribution box
PDP
power distribution panel
PDU
power distribution unit
pool
A set of volumes that are reserved for storing Copy-on-Write Snapshot
data or Dynamic Provisioning write data.
R
RAID
redundant array of independent disks. A disk array in which part of the
physical storage space is used to store user data and parity information,
and another part is used to store a duplicate set of user data and parity
information. This redundant configuration prevents data loss in case a
disk drive within the RAID configuration fails, and enables regeneration
of user data in the event that one of the array's member disks or the
access path to it fails.
RAID group
A set of RAID disks that have the same capacity and are treated as one
group for data storage and recovery. A RAID group contains both user
data and parity information. This allows user data to be accessed in the
event that one or more of the drives within the RAID group are not
available. The RAID level of a RAID group determines the number of
data drives and parity drives and how the data is “striped” across the
drives. For RAID1, user data is duplicated within the RAID group, so
there is no parity data for RAID1 RAID groups.
A RAID group can also be called an array group or a parity group.