MicroNet Technology RAIDBank4 manual Volume Set

2-Understanding RAID

Volume Set

A Volume Set is seen by the host system as a single logical device. It is organized 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 capacity can consume all or a portion of

the disk capacity available in a RAID
Set. Multiple Volume	Sets	can	exist					Free Space
on a group of disks	in a	RAID	Set.
								Volume 1
Additional Volume Sets created in a				Data	Data	Data	Parity
specified RAID Set will reside on all				Data	Data	Parity	Parity Volume 2
the physical disks in	the	RAID	Set.	Disk 1	Disk 2	Disk 3	Disk 4
Thus each Volume Set on the RAID Set
				A 4 Disk RAIDset may contain two volumes. Volume 1 can be
will have its data spread evenly across
				assigned a RAID 5 level of operation while Volume 2 might be
all the disks in the RAID Set.				assigned a RAID 0+1 level of operation.

•Volume Sets of different RAID levels may coexist on the same RAID Set.

•The maximum addressable size of a single volume set is 2 Terabytes.

•Up to eight volume sets can be created in a RAID set

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 re-configuring 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 as following figure:

Before Expansion: Disk Array A, 600GB			After Disk Expansion: Disk Array A, 800GB
		Free Space				Free Space
		200GB				400GB
		Vol 1 (200GB)				Vol 1 (200GB)
		Vol 2 (200GB)
						Vol 2 (200GB)
Disk 1	Disk 2	Disk 3	Disk 1	Disk 2	Disk 3	Disk 4
200GB	200GB	200GB	200GB	200GB	200GB	200GB

The RAIDBank4 controller redistributes the original volume set over the original and newly added disks, using the same fault- tolerance configuration. The unused capacity on the expanded RAID set can then be used to create additional volume sets, with a different fault tolerance setting if required.

Array Roaming

The RAIDbank4 stores configuration information both in NVRAM and on the disk drives, and can protect 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. Should the RAIDBank4 enclosure cease to function, the RAID set disk drives can be moved to another RAIDBank4, inserted in any order, and become instantly available.

RAIDBank4 Owner’s Manual 16