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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.
1.5.3.4 Online RAID Level and Stripe Size Migration
User can do migration on 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 event that
additional physical disks are added to the RAID subsystem. 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.
1.5.4 High Availability
1.5.4.1 Creating Hot Spares
A hot spare drive is an unused online available drive, which is ready to replace a failed disk
drive. In a RAID level 1, 0+1, 3, 5 or 6 Raid Set, any unused online available drive installed
but not belonging to a Raid Set can be defined as a hot spare drive. Hot spares permit you
to replace failed drives without powering down the system. When the RAID subsystem
detects a drive failure, the system will do automatic and transparent rebuild using the hot
spare drives. The Raid Set will be reconfigured and rebuilt in the background while the RAID
subsystem continues to handle system request. During the automatic rebuild process,
system activity will continue as normal, however, the system performance and fault
tolerance will be affected.
IMPORTANT: The hot spare must have at least the same or more
capacity as the drive it replaces.
SAS-to-SATA II RAID Subsystem
Installation and Configuration Manual
22
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