RAID 6 with six 8 TB drives: double-parity safety for high-capacity arrays
RAID 6 with six 8 TB drives uses double distributed parity, giving you 32 TB of usable capacity (4 drives' worth) from 48 TB raw. It can survive any two simultaneous drive failures, which makes it the go-to choice for arrays where rebuild times stretch past 24 hours and the risk of a second failure during rebuild is statistically significant.
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Storage Efficiency
Survives 1 drive failure
How this is calculated
RAID 6 costs two drives' worth of capacity to parity instead of RAID 5's one, but on a 6-drive array that's 33% overhead vs 17%, a reasonable premium for double protection. The write penalty is higher than RAID 5 because the controller must compute and write two parity blocks per stripe, which makes RAID 6 about 10-20% slower on writes than an equivalent RAID 5 array. Read performance is excellent, scaling with the number of data drives (4 in this config). For archival storage, media servers, and backup targets, RAID 6 with large drives is the gold standard.
Verdict
RAID 6 with 6×8 TB is the responsible choice for any array where a rebuild might take more than 24 hours. Double-parity means you can lose a drive, start a rebuild, and still survive a second failure during the rebuild window. The capacity overhead is worth the peace of mind.
Frequently asked questions
When should I use RAID 6 instead of RAID 5?
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