
WiebeTech LLC
SilverSATA V-UR User’s Manual - 11 -
1.3.3.2 Array Roaming
The RAID controller stores configuration information both in NVRAM and on the disk
drives. It can protect the configuration settings in the case of a disk drive or controller
failure. Array roaming allows the administrators the ability to move a complete raid set to
another system without losing RAID configuration and data on that raid set. If a server fails
to work, the raid set disk drives can be moved to another server and inserted in any order.
1.3.3.3 Online Capacity Expansion
Online Capacity Expansion makes it possible to add one or more physical drive to a
volume set while the server is in operation, eliminating the need to store and restore after
reconfiguring 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 an additional volume set. The
expansion process is illustrated as a following figure.
The RAID 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 an additional volume set, with a different
fault tolerance setting if the user needs to change it.
1.3.4 Online RAID Level and Stripe Size Migration
Users 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 and in the event that additional physical
disks are added to the RAID controller. For example, in a system using two drives in RAID
level 1, you could increase capacity and retain fault tolerance by adding another drive. You
then have the option of adding the third 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.
1.4 High availability
1.4.1 Creating Hot Spares
A hot spare drive is an unused online available drive, which is ready for replacing the failure
disk drive. In a RAID level 1, 0+1, 3, or 5 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
controller detects a drive failure, the system will automatically do transparent rebuilds using
hot spare drives. The raid set will be reconfigured and rebuilt in the background while the
RAID controller continues to handle system requests. During the automatic rebuild process,
system activity will continue as normal, however, the system performance and fault
tolerance will be affected.
1.4.2 Hot-Swap Disk Drive Support
The RAID controller has built the protection circuit to support the replacement of SATA II
hard disk drives without having to shut down or reboot the system. The removable hard
drive tray can deliver “hot swappable,” fault-tolerant RAID solutions at prices much less than
conventional SCSI hard disk RAID controllers. We provide this feature for controllers to
provide the advanced fault tolerant RAID protection and “online” drive replacement.
1.4.3 Hot-Swap Disk Rebuild
A Hot-Swap function can be used to rebuild disk drives in arrays with data redundancy such