RAID 5 MTBF issue: will this take 4TB HDDs?

Several articles explain an issue with the MTBF (mean time between failures) being far too high (around 1 in 200, I believe), when drives in RAID-5 enclosures/multi-enclosure set-ups, where the drive pool is greater than 20TB's.

(Additionally, these articles mention the main business storage vendors also have clauses strongly dissuading admins set-up storage as RAID-5 accordingly for 20+TB storage pools.)

a) Given all this, is this enclosure going to be safe to use with 4TB drives (ie. 24TB, in a RAID-5 set-up)?

b) Or should it be a minimum RAID-6 when looking at using 4TB drives in this enclosure?

c) Or perhaps can RAID-5 safely be used, provided one has a completely separate enclosure for backup's (eg. using Time Machine, or something else to do them)?

Confusing to say the least. :-|

  • Asked by James S
  • Mar 21, 2013
PROMISE Pegasus R6 18TB (6 by 3TB) RAID System

PROMISE Pegasus R6 18TB (6 by 3TB) RAID System

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1 Answer from the Community

  • Answer

    Actually, 4T drives will only be agreed from Promise in a few weeks from now. I have 2 units with 6x 4TB drives = total of 24TB in RAID5 means 20TB available.
    BUT these 2 units had several breakout and hangs......
    You should wait to buy agreed 4TB drives !!!

    • Answered by Patrick L
    • Jun 15, 2013