RAID 6 is a new entry into the storage arena. Vendors have different marketing terms for RAID 6, but essentially, it's RAID 5 with an extra parity disk that adds redundancy. This allows you to lose up to two drives in a RAID 6 array without data loss. RAID 6 requires a minimum of four drives.
RAID 60 is two (or more) RAID 6 groups striped together. The Sun Fire X4150 we tested had eight drives on two channels, so it nicely split into two RAID 6 groups striped together to make one RAID 60. This further reduces the risk of drive loss. With RAID 60, you can lose up to four drives, compared with the two-drive limit in RAID 6.
However, this added redundancy comes at the cost of additional parity disks. Furthermore, because RAID 60 is a striped collection of RAID 6 arrays, each RAID 6 array must remain consistent. Otherwise, data will be lost.
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