Proware DP-503-F4A3, Installation And User Manual, Page: 21 / 84

DP-503-F4A3 RAID SUBSYSTEM
Installation and User Manual 21
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 Background Mode 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 Volume Sets without waiting
for the initialization to be completed. One disadvantage of this is that the initialization process takes
longer time. In Foreground Mode initialization, the initialization process is faster but must be
completed first before the Volume Set is ready for system access.
1.5.3.2 Array Roaming
The RAID subsystem stores configuration information both in NVRAM and on the disk drives. This
protects the configuration settings in the case of a disk drive or controller failure. Array roaming
allows the administrator the ability to move a complete Raid Set to another system without losing
RAID configuration and data on that Raid Set. If a RAID enclosure fails to work, the Raid Set disk
drives can be moved to another enclosure and inserted in any order.
1.5.3.3 Online Capacity Expansion
Online Capacity Expansion makes it possible to add one or more physical drives to a Raid Set, while
the server is in operation, eliminating the need to backup and restore after reconfiguring the Raid Set.
When disks are added to a Raid Set, unused capacity is added at 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 be
used to create additional Volume Set. The expansion process is illustrated as follows.
The RAID subsystem controller redistributes the original Volume Set over the original and newly
added disks, using the same RAID level configuration. The unused capacity on the expand Raid Set
can then be used to create an additional Volume Sets, with a different RAID level setting as needed
by user.