RAID-5 vs. RAID-6 Storage Compared

There is a performance impact when you use RAID-6 (you update two parity drives instead of just one), but RAID-6 is recommended by Red Hat since drive current drive capacities increases the probability that a double fault will occur while repairing a failed drive.

For example, notice the following possible scenario with a RAID-5 set that contains 4 data drives + 1 parity drive:

Time 1: Drive 1 fails
Time 2: RAID rebuild starts and every block on every drive requires reading
Time 3: On disk 3, disk error reading on block 7
Time 4: On disk 4, disk error reading on block 100,000
Time 5: On disk 2, disk error reading on block 200,000

Latent errors with today's drives are extremely common (almost a certainty). With RAID-5 in the above scenario, three RAID-5 stripes of user data are lost. With RAID-6, you can rebuild the failed sectors from the second parity drive (assuming it does not have the same bad sectors that failed on the other drives).

For Red Hat Storage, Red Hat highly recommends customers keep all of their data as safe as possible. Data safety is paramount to performance.