Accusys ExaRAID GUI - Manual (Page 275)

Appendix
B-6
capacity change, RAID operations are still available to protect data and
serve requests from host computers.
• Concurrent logical disk capacity and disk group expansion
The logical disk capacity expansion can also be done simultaneously with
disk group expansion, and as a result, users can expand the capacity of a
LUN by adding more drives to its disk group. Without logical disk capacity
expansion, the administrator is forced to create a new LUN after the disk
group expansion is done. To use the capacity on the new LUN, either extra
data management efforts like file system or application reconfiguration are
needed, or the administrator needs to deploy volume management
software on the host computer, which leads to extra cost, complexity, and
efforts.
• Autonomous free space management
The free space on a disk group is managed as free chunks. A free chunk is
created when an administrator deletes a logical disk or shrinks its capacity.
Free chunks are for creating new logical disks or for expanding a logical
disk. By visualizing the free space with easy management utilities, an
administrator can easily manage the free space and avoid waste.
• Online de-fragmentation
To have a continuous free space for new logical disks, discontinuous free
chunks on a disk group can be consolidated into one big free chunk. This is
accomplished by a background task to move the data on the disk group.
Without the online de-fragmentation, the administrator needs to manually
move the data of logical disks, and unacceptable system downtime is thus
introduced.
• Online volume expansion and shrink
The capacity of a volume can be online expanded by adding the logical
disks to the volume, which concatenates the space of each logical disk to
form a larger capacity. Because the expansion is done instantly without
incurring any background tasks, users can quickly start using the added
capacity without waiting. Users can also reduce the capacity of a volume
by removing the concatenated logical disks. Freely expanding and
shrinking a volume enables efficient storage resource management.
B.7 Adaptive Performance Optimization
The performance is one of the most important values of a storage system,
because higher performance means the capability to support larger
organization, more transactions, and higher productivity. The RAID controller
firmware fully utilizes the state-of-art storage hardware technologies to
deliver the best-of-breed performance. The administrator can further
enhance the performance by setting the extensive configurable
performance parameters offered by the firmware and monitor the
performance regularly. The firmware also provides adaptive optimization