Installation guide

Chapter 1. Introduction
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1.1.3 Foreground Availability/Background Initialization
RAID 0 and RAID 1 volume sets can be used immediately after creation
because they do not create parity data. However, RAID 3, 5, 6, 30, 50 or 60
volume sets must be initialized to generate parity information. In Background
Initialization, the initialization proceeds as a background task, and the volume
set is fully accessible for system reads and writes. The operating system can
instantly access the newly created arrays without requiring a reboot and without
waiting for initialization to complete.
Furthermore, the volume set is protected against disk failures while initialing. If
using Foreground Initialization, the initialization process must be completed
before the volume set is ready for system accesses.
1.1.4 Online Array Roaming/Offline RAID set
The RAID subsystem stores configuration information 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 configuration and data on that RAID
set. If a server fails to work, the RAID set disk drives can be moved to another
server and inserted in any order.
1.1.5 Online Capacity Expansion
Online Capacity Expansion makes it possible to add one or more physical drives
to a volume set, while the server is in operation, eliminating the need to store
and restore after reconfiguring the RAID set. When disks are added to a RAID
set, unused capacity is added to the end of the RAID set. Data on the existing
volume sets residing on that RAID set is redistributed evenly across all the disks.
A contiguous block of unused capacity is made available on the RAID set. The
unused capacity can create additional volume set.
The expansion process is illustrated in the following figure.
Disk0 40GB Disk1 40GB Disk2 40GB
Free Space = 40GB
Volume 1 = 40GB (D: )
Volume 0 = 40GB (C: )
Array-A 120GB
Before Array Expansion