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SteveRD

Fail Drive Test

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Posted (edited)

Hello,

 

I am currently running a trial and want to test a drive failure to I understand what happens within Unraid. I have pulled one of the HDDs, but the array is still reporting no issues? Is there something I am missing?

 

Thanks,

Edited by SteveRD

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Have you tried to access files on the missing drive? 

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Yes no issue which is great, but i expected an error in Unraid telling me which drive needs to be replaced? 

 

Thanks,

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The drive, or perhaps more precisely, the "slot" the drive is assigned to, will be disabled by Unraid when a write to the drive fails. This could be an actual write, or it could possibly be a write-back from the parity calculation when a read to it fails. After it is disabled, Unraid will emulate it from the parity calculation until it is rebuilt.

 

Unraid is NOT RAID, each drive isn't required to allow access to the data on the array. Each disk is an independent filesystem. Until a read or write is asked for on that drive, Unraid will not notice since it will not try to access the disk. Possibly the disk was even already spun down when you pulled it, since Unraid will spin down unused disks after a (configurable) time.

 

A disabled disk is shown with a red X next to it, and if you have Notifications setup correctly, you will also get an alert. You should setup Notifications to alert you immediately by email or other agent as soon as a problem is detected.

 

If you only have single parity, then when a disk is disabled, you no longer have any redundancy, though the data for that disk can still be accessed for read or write using the parity calculation. Dual parity allows 2 disabled disks before redundancy is lost.

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OK thanks, i think i'm not getting the disabled drive as i'm not writing data to that drive. I only received the disabled drive when running a read-check, which means you could have a fault drive for 23 hours (assuming once a day check). Will do a few tests now!

 

Thanks,

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I would think that you didnt try to actually read any file on the pulled drive. The read would have failed, which means that an immediate attempt to write to the drive would happen (which would obviously fail) which would trigger a notification (assuming you've set them up)

Sent from my NSA monitored device

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1 hour ago, SteveRD said:

I only received the disabled drive when running a read-check, which means you could have a fault drive for 23 hours (assuming once a day check)

Do you mean a parity check? Most people only run a parity check once per month. Parity check isn't needed to maintain parity, it is maintained realtime whenever a data drive is written.

 

I don't see what difference it makes whether the unused disk is noticed during the time it is unused. As soon as it is accessed you would get the notification.

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As long as your actually trying to read off the "Correct" Drive using /mnt/disk* or which ever via your PC/Mac.  I'm saying this because if your using a Cache drive in a User Share files might not actually be on the drive yet. Unless of course you know the files are on the removed drive and I'm rambling again. Lol

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