easyRAID E6, User Manual

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Introduction
RAID level 5 arrays have unique performance characteristics :
The data can be recalculated or regenerated, using parity,
when any drive in the array fails.
When the failed drive is replaced, either automatically if the
subsystem contained a hot spare drive, or by user intervention
during a scheduled maintenance period, the system will be
restored its full data redundancy configuration by rebuilding all
of the data that had been stored on the failed drive onto the
new drive. This is accomplished using parity information and
data from the other data disks. Once the rebuild process is
complete, all data is again protected from loss due to any
failure of a single disk drive.
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