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We're building an array of 12x 2TB drives in a RAID60 array using an Adaptec hardware card.

It's taking a long time to build/verify, and performance is slow. We've worked out that it will be around two weeks before the build/verify completes.

I'm currently tossing up whether to drop the whole thing and initialise using the clear method (ie zero out all the disks), but there is already 2TB of data on there so it's no small task.

A big concern is what happens if a disk fails during the build/verify phase - is our data safe? I can't find any documentation on this.

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Two weeks!!! That's seriously not right, you have a problem there.

Anyway, with R6/60 you're fine for losing at least one other disk during this time.

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I think i'm right in saying you could lose one more from the same section of the raid 0, or up to two more from each of the other sections of the raid 0. How many that is depends on if you have 2x6 disk RAID6's or 3x4 disk RAID6's. I assume 2x6 (as that's more sane imho), which means at worse you can afford to lose one more, and at best you can lose 3 more, –  Sirex Jul 3 '13 at 22:49
    
@Sirex - yeah, you're right, there's a reason I worded my answer as I did - because there are failure cases even with R6 where you could lose the array by having the wrong additional disks die - but the OP asked about a single disk and as it happens they'd be fine in that scenario. Not a fan of R60 but in this case it probably does make some sense. Worried about the rebuild time though. –  Chopper3 Jul 4 '13 at 7:49
    
Thanks guys. I also emailed Adaptec and surprisingly got a response! "Yes, redundancy is present during the Array build task on a RAID 60 Array, although as you will have noticed the performance is reduced during the build process. " –  mobiusnz Jul 5 '13 at 1:55
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If it is a RAID 60 array this behavior is normal. Since the server is used during the rebuild the rate of rebuild can be slow. In RAID 60 you have two RAID 6 arrays(two arms) which are striped. So we have a tolerance of two disk in each arm of the RAID 6 arrays.

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