When you replace the failed drive, the data for the logical drive undergoes
expansion and returns to the original striping scheme.
Advantages and disadvantages
RAID level-5EE offers the following advantages and disadvantages.
Advantages
v 100% data protection
v Offers more physical drive storage capacity than RAID level-1 or
level-1E
v Higher performance than RAID level-5
v Faster rebuild than RAID level-5E
Disadvantages
v Lower performance than RAID level-1 and level-1E
v Supports only one logical drive per array
v Cannot share a hot-spare drive with other arrays
v Not supported on all controllers
More information
v Understanding RAID technology
v Understanding stripe-unit size
v Selecting a RAID level
v RAID level-0
v RAID level-1
v RAID level-1 Enhanced
v RAID level-5
v RAID level-6
v RAID level-x0
v RAID volumes
Understanding RAID level-6
RAID level-6 is similar to RAID level-5 but with two sets of parity information
instead of one. RAID level-6 stripes blocks of data and parity across all drives in
the array like RAID level-5, but adds a second set of parity information for each
block of data.
When you assign RAID level-6 to an array, the capacity of the array is reduced for
data-parity storage (the exact amount depends on the size of the drives in the
array). The second set of parity information is added to improve fault tolerance.
RAID level-6 can handle two simultaneous drive failures, where other single RAID
levels can handle, at most, only one.
RAID level-6 requires a minimum of four drives and supports a maximum of 16
drives. The maximum stripe-unit size depends on the number of drives in the
array.
The following illustration is an example of a RAID level-6 logical drive.
Chapter 3. Using ServeRAID Manager 43
