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Chapter 9
Redundant Controller
Before You Begin...
What Is Redundant Controller? Why The Need For Redundant
Controller?
Redundant controller is using two or more RAID controllers in the
same RAID system. If you have two controllers, both must be working
normally and capable of monitoring each other at the same time. Each
controller serves its own I/O requests. When a controller fails to
function, another controller will temporarily take over. One of the goals
of a RAID system is to provide a stable storage architecture. The
functionality of a redundant controller increases the availability of the
RAID system.
All electronic components have its lifetime. A simple memory parity
error may sometimes cause the controller to completely hang up. This
is the reason why we need a redundant controller -- to minimize the
down-time chance of a RAID system.
Write-Back Cache: Enabled or Disabled?
There is always a lot of data stored in the cache memory. When using
the AA-3102RS in a redundant controller configuration, the cache
memory's Write-Back mode will be disabled automatically the
redundant controller feature is enabled. Instead, the cache memory
will use Write-Through mode. This is to avoid data loss if a controller
fails to function.
Chapter 9 Redundant Controller
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