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Does RAID 6 takes less time to rebuild than RAID 5 if only one drive fails? Many thanks.

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migrated from stackoverflow.com Aug 29 '11 at 20:42

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They should both take the same amount of time since only a single parity calculation is necessary.

Some implementations may do both, which may take longer depending on the implementation. Some HBAs can do both parity calculations at the same time, others cannot. Software might take double the CPU power, again depends on the implementation.

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With a second parity stripe, the rebuild process should be significantly longer.

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Sorry @Chris S, this is not entirely true. If the failed drive has both stripes, the distributed double parity will need to rebuild. Its well known that RAID 6 systems carry a heavy write performance burden due to the additional parity calculation and the additional memory interrupts. This can be assumed with the rebuild process as well. –  Fergus Aug 29 '11 at 21:13
    
both parity or not, there's a fixed amount of data on the disk, it has to be calculated from the other disks. In most implementations it doesn't even matter if the data is parity or not, it's all just the other n disks' data xored. This isn't a write operation where x data gets turned into x+2. –  Chris S Aug 30 '11 at 2:19
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