Can I trust parity or should I rebuilt?

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The only way to have parity valid would be if you clear each and every sector on the drive to zero before it is removed.  Copying files off does not do that, and so the parity will not be valid after the drive removal.

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The following is copied from another thread that details how to remove a disk without losing parity.   VERY IMPORTANT NOTE:  The command shown will write zeroes to the selected drive (while maintaining parity) ... be CERTAIN you have selected the correct drive.     When the operation completes (it will take a few hours, as it's writing every sector on the drive), that drive will be all zeroes -- which means you can remove it and parity will still be valid.


While this is not any quicker than just doing a parity sync, it DOES provide a method to remove drives without impacting parity ... so you can then safely do a New Config without the zeroed drive(s) and check the "Parity is already valid" box.




If you really want to remove a drive and leave parity undisturbed, this will work:

1. Start array in Maintenance mode.  This ensures no file systems are mounted.

2. Identify which disk you're removing, let's say it's disk3.  Take a screen shot.

3. From the command line type:


dd bs=1M if=/dev/zero of=/dev/md3   <-- 'md3' here corresponds to 'disk3'
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