Installation guide

Software Operation Manual
10
1.1.6 Online RAID Level and Stripe Size Migration
User can migrate both the RAID level and stripe size of an existing volume set,
while the server is online and the volume set is in use. Online RAID level/stripe
size migration can prove helpful during performance tuning activities as well as
in the event where those additional physical disks are added to the RAID
subsystem. Before the invention of RAID level and stripe size migration,
changing the RAID level and stripe size of a RAID system meant backing up all
data in the disk array, re-creating disk array configuration with new RAID level
and stripe size, and then restoring data back into RAID system. For example, in
a system using two drives in RAID level 1, you could add capacity and retain
fault tolerance by adding one drive. With the addition of third disk, you have the
option of adding this disk to your existing RAID logical drive and migrating from
RAID level 1 to 5. The result would be parity fault tolerance and double the
available capacity without taking the system off.
1.1.7 Global/Dedicated Hot Spares
A hot spare is an unused online available drive, which is ready for replacing the
failure disk. The hot spare is one of the most important features that RAID
controllers provide to deliver a high degree of fault-tolerance. A hot spare is a
spare physical drive that has been marked as a hot spare and therefore is not
a member of any RAID set. If a disk drive used in a volume set fails, then the hot
spare will automatically take its place and the data previously located on the
failed drive is reconstructed on the hot spare.
Dedicated hot spare is assigned to serve one specified RAID set. Global hot
spare is assigned to serve all RAID set on the RAID controller. Dedicated hot
spare has higher priority than the global hot spare. For this feature to work
properly, the hot spare must have at least the same capacity as the drive it
replaces. The host spare function only works with RAID level 1, 1E, 3, 5, 6, 10,
30, 50, or 60 volume set.
The “Create Hot Spare” option gives you the ability to define a global / dedicated
hot spare disk drive. To effectively use the hot spare feature, you must always
maintain at least one drive that is marked as a global hot spare.
Disk0 40GB Disk1 40GB Disk2 40GB
Free Space = 80GB
Volume 1 = 40GB (D: )
Volume 0 = 40GB (C: )
Array-A 160GB
After Array Expansion (Adding One Disk)
Disk3 40GB