MicroNet Technology Network Device RAIDBank4 - Manual (Page 17)

RAIDBank4 Owner’s Manual 17
Hot Swappable Disk support
Your RAIDBank4 has a built in protection circuit to support replacement of disk drives
without having to shut down or reboot the RAID. In case of drive failure, the failed drive can
be removed from the RAIDBank4 and replaced with a new drive without disrupting dataflow
to the host computer.
Instant Availability/Background Initialization
RAID 0 and RAID 1 volume set can be used immediately after the creation, whereas RAID
3 and 5 volume sets must be initialized to generate parity information. RAIDBank4 features
both foreground and background initialization modes for RAID 3 and RAID 5 volumes- In
background mode, the initialization proceeds as a background task and the volume set is
fully accessible for system reads and writes without requiring a reboot and waiting for the
initialization completion. Furthermore, the RAID volume set is also protected against a single
disk failure while initialing. Background initialization takes longer to complete and host
disk access will be slower during the initialization process. Foreground Initialization must
be completed before the volume set is ready for system accesses, but the RAID Initialization
completes faster.
Online RAID Level and Stripe Size Migration
Users can migrate both the RAID level and stripe size of an existing volume set, while the
RAIDBank4 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 at the addition of physical
disks to the RAIDBank4. 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 by migrating from
RAID level 1 to 5. The result would be parity fault tolerance and double the available capacity
without taking the system offline.
Hot Spare Drives
A hot spare drive is an unused online available drive predesignated for replacing a failed
disk drive. 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 automatically
without powering down your RAIDBank4. When your RAIDBank4 detects a drive failure in a
RAID 1,10,3 or 5 volume sets the system will automatically and transparently rebuild using any
available hot spare drive(s). The volume set(s) will be reconfigured and rebuilt in background,
while the RAIDBank4 continues to handle system requests. During the automatic rebuild
process, system activity will continue as normal, but system performance will be reduced and
the affected volume(s) will not be fault tolerant until the rebuild process is complete.
Hot-Swap Disk Rebuild
A Hot-Swap function can be used to rebuild disk drives in arrays with data redundancy such
as RAID level 1, 10, 3, and 5. If a hot spare is not available at time of drive failure, the failed
disk drive must be replaced with a new disk drive so that the data on the failed drive can be
rebuilt. Upon insertion of a replacement disk, the RAIDBank4 automatically and transparently
rebuilds failed drives in the background with user-definable rebuild rates. The RAIDBank4
will automatically restart the system and the rebuild if the system is shut down or powered
off abnormally during a reconstruction procedure condition. Please note that the affected
volume(s) will not be fault tolerant until the rebuild process is complete.
2-Understanding RAID