User`s guide

Introduction
1-14
1.4.2 Volume Set
A Volume Set is seen by the host system as a single logical device. It is orga-
nized in a RAID level with one or more physical disks. RAID level refers to the
level of data performance and protection of a Volume Set. A Volume Set ca-
pacity can consume all or a portion of the disk capacity available in a RAID
Set. Multiple Volume Sets can exist on a group of disks in a RAID Set. Addi-
tional Volume Sets created in a specified RAID Set will reside on all the physi-
cal disks in the RAID Set. Thus each Volume Set on the RAID Set will have its
data spread evenly across all the disks in the RAID Set.
1. Volume Sets of different RAID levels may coexist on the same RAID Set.
2. Up to 16 volume sets can be created in a RAID set.
In the illustration below, Volume 1 can be assigned a RAID 5 level of opera-
tion while Volume 0 might be assigned a RAID 0+1 level of operation.
1.4.3 Easy of Use features
1.4.3.1 Instant Availability/Background Initialization
RAID 0 and RAID 1 volume set can be used immediately after the creation.
But the RAID 3, 5 and 6 volume sets must be initialized to generate the
parity. In the Normal Initialization, the initialization proceeds as a background
task, the volume set is fully accessible for system reads and writes. The
operating system can instantly access to the newly created arrays without
requiring a reboot and waiting the initialization complete. Furthermore, the
RAID volume set is also protected against a single disk failure while initialing.
In Fast Initialization, the initialization proceeds must be completed before the
volume set ready for system accesses.
1.4.3.2 Array Roaming
The RAID subsystem stores configuration information both in NVRAM and on
the disk drives It can protect the configuration settings in the case of a disk
drive or controller failure. Array roaming allows the administrators the ability to
move a completely raid set to another system without losing RAID configura-