Dont know how to fix it Please help!

[whitewraith]

Ok, Unraid does not like me at all. I finally got all my data transferred over to the array. I figured now is a good time to get parity disk assigned and start that. That is going fine. Kids start watching plex then plex stops working and Unraid is stating there is a I/O error disk one sdc and there is now a red x next to it.  I am wondering why it did this so i stop the array and stop the parity as I dont think it is gonna be a good one anyway. I unassigned the disk and mount it in unassigned app and Krusader seems fine with it and all files are accounted for. I then plug it back in and it wont let me add it to the array nor will it let me add the parity drive back to the array. How can I fix this issue. I know that it wouldn't let me add disks to the array with the parity drive assigned and parity not completed, so i removed the parity drive thinking it would let me add disk 1 back to the array but it wont. I have attached the diagnostics for you all to peruse and help me out please.  How do I get this back up and going since I guess the disk is ok now.

mediahog-diagnostics-20200802-1344.zip

[trurl]

Until you get more experience, please ask for advice before making any changes to disk assignments. Removing disks and mounting them outside the array, for example, will invalidate parity. Sounds like parity wasn't valid yet anyway, but just thought I would mention it since it seems like something you might do without asking for advice.

 

When syslog starts, you don't have anything assigned as parity or disk1. I guess we will just have to assume disk1 is OK, or at least as good as it we can make it, since you may not have valid parity.

 

I assume this is the disk you were going to use as parity:

Serial Number:    ZL23XXAR

 

Go to Tools - New Config. Assign all disks including parity exactly as before. You must be very careful and not accidentally assign a data disk to the parity slot, or the data will get overwritten by parity.

 

Then start the array and let parity build. I recommend waiting until you have valid parity before using the array just in case you have any other problems. 16TB may take more than a day.

[whitewraith]

8 minutes ago, trurl said:

Until you get more experience, please ask for advice before making any changes to disk assignments. Removing disks and mounting them outside the array, for example, will invalidate parity. Sounds like parity wasn't valid yet anyway, but just thought I would mention it since it seems like something you might do without asking for advice.

 

When syslog starts, you don't have anything assigned as parity or disk1. I guess we will just have to assume disk1 is OK, or at least as good as it we can make it, since you may not have valid parity.

 

I assume this is the disk you were going to use as parity:

Serial Number:    ZL23XXAR

 

Go to Tools - New Config. Assign all disks including parity exactly as before. You must be very careful and not accidentally assign a data disk to the parity slot, or the data will get overwritten by parity.

 

Then start the array and let parity build. I recommend waiting until you have valid parity before using the array just in case you have any other problems. 16TB may take more than a day.

Thankyou!!!  I did not mean to screw it all up. I stopped the array and everything before taking the disks out of the array. I will let it do parity to completion before using plex again for sure.  I appreciate your patience with a new UnRaid user. I was just trying to find out why the disk went bad in the first place.

[trurl]

1 minute ago, whitewraith said:

I stopped the array and everything before taking the disks out of the array.

But mounting an array disk outside the array will invalidate parity whether or not the array is stopped. The removed disk is modified outside the array and no longer matches parity, so parity is invalid.

 

And when you put it back and start the array it will look like everything is OK since Unraid doesn't really know what you might have done with the array stopped. So then when you have a problem that requires valid parity to recover, it won't work because that disk is out-of-sync.

 

Parity by itself can't recover anything. All other disks are also required by the parity calculation.

[whitewraith]

So if the disk has issues again before parity completes, what should I do? I hate to think that the data is just lost, is there a way to transfer the data to a new disk and keep the array and parity in sync.

[trurl]

3 minutes ago, whitewraith said:

So if the disk has issues again before parity completes, what should I do? I hate to think that the data is just lost, is there a way to transfer the data to a new disk and keep the array and parity in sync.

Parity isn't a backup, so whether or not you have valid parity, you must have another copy of anything important and irreplaceable, preferably on another system.

[whitewraith]

1 hour ago, trurl said:

Parity isn't a backup, so whether or not you have valid parity, you must have another copy of anything important and irreplaceable, preferably on another system.

So what is parity? Doesn't it allow for one disk to fail and in that event allow you to rebuild the data that was lost?

[trurl]

36 minutes ago, whitewraith said:

So what is parity? Doesn't it allow for one disk to fail and in that event allow you to rebuild the data that was lost?

Yes, parity plus all remaining disks allow the data for a missing disk to be calculated.

 

Parity is a common concept in computers and communication, and its meaning is basically the same wherever it is used. Parity is just an extra bit that allows a missing bit to be calculated from all the other bits.

 

Here is the wiki on Unraid parity:

 

https://wiki.unraid.net/UnRAID_6/Overview#Parity-Protected_Array

[whitewraith]

Got it, don't call parity a backup cause it isn't technically a backup but it will allow you to recover data in the event of a disk failure.  So more of a fail safe i suppose rather than a true backup.  I am not that unfamiliar with computers believe it or not. I am however unfamiliar with UnRaid as an OS and haven't had much use for Linux in my day to day activities. I do appreciate your help with fixing my issue today, Thankyou.