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I have a workstation that uses an adaptec RAID 71605 controller with 4x8TB WD drives in a RAID5 config. One of these drives failed, and after replacing it and rebuilding the RAID, a lot of the data stored on the RAID is corrupted. The Hyper-V machines do not start any more, and a lot if graphics are just broken or have a lots of artefacts.
I have but the controller in a different workstation, with the same result. I then swapped the controller, but the data is still corrupted. Checkdisk and rebuilding the array did not help
Now I am very curious as to why that happened?
The controllers only job is to assure that a drive failure is non-critical, and that was not the case here. Is that something "normal" that can happen? Is there a way to protect for such errors? And most importantly: Is there a way of recovering the files?
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    See the section on RAID 5 in this Q&A serverfault.com/questions/339128/… and continue with what a URE is here: serverfault.com/q/812891/546643 - additionally, no RAID level is a substitute for regular backups
    – Bob
    Feb 12, 2021 at 8:41
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    Every few weeks we get someone come to this site with exactly the same story - RAID 5 is dangerous, personally I think it shouldn't be allowed to be sold/provided by controller manufacturers. Sorry it's you this time, oh and only R1/10 and R6/60 are reliable, oh and ZRAID/ZFS if you're into that.
    – Chopper3
    Feb 12, 2021 at 10:55
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    Hi, and thanks for your comments. Of course we have a backup strategy, and its restoring at the moment, but restoring 24TB of data takes it's sweet time. I guess I am manly interested as to what exactly happend? Like what caused it to fail? Bad thing is that we are scheduled to phase out our RAID5 workstations and the end of the year and replacing them with new controllers and a raid 6 + hotspare config. Guess it was just bad luck
    – smiet
    Feb 13, 2021 at 9:06
  • @Chopper3 RAID 5 is dangerous That's a bit strong. It wouldn't surprise me in this case that more than one drive was going bad, but a lot of the bad sectors were never read for a while so they were never noticed. Once one drive failed, the rebuild exposed the latent issues. A RAID6 array is less susceptible to such failures, but they're still possible especially if you do something like creating a RAID 6 array from 19 8TB drives (with a 1 MB segment size "because bigger is faster"...) But a RAID 5 array of 5 400GB SSDs would be fine (yeah, two 1.6TB RAID 1 SSDs would be better, but...) Feb 13, 2021 at 13:53
  • Google 'raid 5 bad' or similar - this is the first thing that came up for me, and it's over 11 years old - so yeah, dangerous; zdnet.com/article/why-raid-5-stops-working-in-2009
    – Chopper3
    Feb 15, 2021 at 12:47

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