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Parity is not the biggest?

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Posted (edited)

I just setup a new server. I'm still on my trial. Everything was done and working OK however I rebooted the server and now unraid says the parity drive is not the biggest drive. I have a 4tb parity, a 4tb data drive of the exact same model and another 1tb data drive. Why would unraid think the parity drive is not the proper size?

Edited by joker_927

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What motherboard do you have and what Bios version is it running?   It sounds as if the Bios might have tried to create a  HPA area on the parity disk (thus effectively shrinking it).


Providing the system diagnostics zip file (obtained via Tools->Diagnostics) should allow for confirmation of whether this is what has happened.

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Old GigaByte Motherboards used to do this if I recall.

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You both nailed it. I am using an older gigabyte motherboard. It turns out the CMOS battery had died so unplugging the computer to move it (a simple task) meant the bios was cleared which meant a new HPA section was written to the disk. Luckily my board has a setting to turn "BIOS HDD backup" off. However the data was already written to the drive. I found some other posts that taught me how to use the hdparm command to remove the data. That fixed the issue and a 10 hour parity rebuild means I'm back up and running. Also, I replaced the CMOS battery.


What a wierd gremlin. All I did was move the computer!


Thanks for the help



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5 minutes ago, joker_927 said:

Luckily my board has a setting to turn "BIOS HDD backup" off.

As you found out, that setting is turned on by default when the CMOS is reset. Investigate whether there may be a BIOS update that changes the default behaviour, or be aware that you may have to go through this again. Next time you may not be as lucky and need to rebuild a data drive at the same time it decides to corrupt a working drive, rendering recovery much more difficult.

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