UltraTrak SX4000, SX8000 & RM8000 User Manual
30
Critical & Offline Arrays
A fault tolerant array goes “critical” when a drive is removed or fails. Due to the
fault tolerance of the array, the data is still available and online. However, once
the array goes critical, the array has lost its fault tolerance, and performance may
be adversely affected. If the fault was caused by a drive that was removed, the
drive should be replaced by another drive, either identical or larger, in order for
the RAID system to rebuild and restore optimal configuration.
A non-fault tolerant array goes “offline” when a drive is removed or fails. Since
the array is not fault tolerant, the data stored in the array is no longer accessible.
If the drive was removed, then it should be replaced to restore accessibility to the
array. If the drive failed, then the entire array must be deleted and re-initialized
since all data is considered lost.
Rebuilding/Synchronizing Fault Tolerant Arrays
Though a critical array can continue storage operations, it no longer offers fault
tolerance and should be addressed as soon as possible by replacing the missing
or failed drive(s).
Rebuild takes a replacement drive, assigns it to the array, and then writes the
redundancy data to it. Once the rebuild process is complete, the array status is
upgraded from “critical” to “functional” and fault tolerance is restored.
Synchronization is a preventative maintenance measure used to avoid problems
with data integrity. Synchronizing simply recalculates redundant data (similar to
the rebuild process) and matches the data on the drive(s).
To synchronize the array, go to the
Configuration
menu and select
Configure
Array
; then select
Advance Features
and choose
Synchronize Array
.
When a Disk Drive Fails
The UltraTrak provides both audible and visual indicators alerting you of a drive
failure. The following occur when a disk drive fails or goes offline:
•
Continuously produces short beeps every two seconds when a drive fails.
•
Continuously produces long beeps every 15 seconds when a drive is offline.
•
The Status LED on the front panel is yellow.
•
The disk drive Status LED (inside front panel door) is red.
•
The LCD displays a status message about the failure.
A fault tolerant array goes “offline” when two disk drives fail or are removed. It will
also go “offline” when it encounters a bad sector on a disk drive while rebuilding
(see page 58). The data stored in the array is intact but it is no longer accessible.
At this point, you must determine the cause of the problem and take corrective
action. Once the array is restored to “critical” condition, you can access your
data. When restored to “functional” condition, fault tolerance is restored.
