March 2013
Dell EqualLogic Configuration Guide v14.1
4-30
4
Capacity planning
4.1
RAID 6 drive layouts and total reported usable storage
RAID6 (striped set with dual distributed parity) combines N disks in an arrangement where each stripe
consists of N-2 disks capacity for data blocks and two disks capacity for parity blocks. Each parity
block generates parity using a different view of the data blocks depending on the RAID 6
implementation. RAID 6 can tolerate up to two drive failures per RAID stripe set at the same time
without data loss. RAID 6 is not recommended for workloads consisting mainly of random writes.
Using a RAID 6 policy, Table 11 shows the drive layouts that are enforced based on the number of
drives in each array/hot spare configuration, and the total usable storage available for each model.