I have a 5 disk array.  Disk two died. I would like to remove disk 5 (has no data on it currently) and use it to replace disk 2 (with lots of data on it). 

 

What is the best way to make this happen?

 

I didn't have much luck searching for this topic but I'm sure I didn't use the right terms or something...

 

Thanks!!

 

Chris

I have a 5 disk array.  Disk two died. I would like to remove disk 5 (has no data on it currently) and use it to replace disk 2 (with lots of data on it). 

 

What is the best way to make this happen?

 

I didn't have much luck searching for this topic but I'm sure I didn't use the right terms or something...

 

Thanks!!

 

Chris

You cannot do that and have the array automatically rebuild disk 2 via parity.

 

However, you can, right now, copy from the disk that died (disk 2) to the disk that is good (disk 5) all the files using your PC's file explorer, or better yet, using midnight commander (mc) built into unRAID.

 

Once you have finished copying the files, and everything is on disk 5 that used to be on disk 2, you can then

stop the array,

power down,

remove the defective drive (moving the drive 5 diver physically to slot2 if you desire, it really does not matter),

power up,

go to the devices page, un-assign disk 2 that is no longer there and make the assignments correct based on where you moved the drives physically. 

Then, go back to the main page, check the checkbox under the Restore button and press it.

Pressing it will rename your super.dat file to super.old.  This will cause the unRAID server to build a new super.dat file and to also force a complete re-build of parity based on the existing working and configured drives when the array is next started.

 

Then, I think you might then get to check the checkbox under  "Start", and press it to start the array.  A full parity calculation will begin.

Once the new parity is calculated, without the defective disk, your array will be protected from a single disk failure once more.

 

Depending on how much data was on disk2, this whole set of steps could take a while, as when copying files from disk2  to disk 5 the original contents are being re-constructed by reading the contents of all the other remaining data and parity disks in the server. (In other words, expect it to take many hours, especially if you use the PC's file explorer, as the data would also then have to go from the server, to the PC and back across the LAN as it is copied.)

 

Remember to copy the files off of disk2 before you do anything else.

This is one of the very few times that pressing the button labeled "restore" is the correct action.  It forces the server to rebuild parity based on the current assigned and working disks.

 

It is as much time (or more) to rebuild this way as it is when you get a new replacement disk, but that might not be possible for you at the moment. 

 

Whatever you do, do NOT press "Restore" if there are any files on the failed disk you want to copy to its replacement. it does NOT restore data.. it only restores the array to an initial state before it calculated parity and forces a rebuild based on the currently assigned and working drives.  Pressing "restore right now, before you do anything to copy the data on disk2 elsewhere, will cause the array to  forget it ever had a disk2, or any of the data on it.

 

Joe L.

I have a 5 disk array.  Disk two died. I would like to remove disk 5 (has no data on it currently) and use it to replace disk 2 (with lots of data on it). 

 

What is the best way to make this happen?

 

I didn't have much luck searching for this topic but I'm sure I didn't use the right terms or something...

 

You cannot get unRAID to rebuild data on disk5 from disk2 using the disk replacement method.  You would need to get a new disk of >= size of disk2.  Although disk5 may be empty from your perspective, it is still part of the parity protected set.  The data stored on each of its sectors are critical to rebuilding disk2.

 

However, you can, right now, copy from the disk that died (disk 2) to the disk that is good (disk 5) all the files using your PC's file explorer, or better yet, using midnight commander (mc) built into unRAID.

 

In my half awake stupor, I didn't quite understand this statement.  After rereading a couple times I realized what Joe L. was saying.  When a disk fails in the array, unRAID "simulates" the failed disk.  This is how you can access the data on disk2.  You can therefore copy the simulated disk2 data to the actual disk5.  The performance will likely be poor, even using MC, but would enable you to get the data copied off disk2 without the need to buy another disk.

 

Be careful with the restore button.  It is easy to go from a recoverable state to a non-recoverable state.

Ok guys I'll give it a shot tonight.  Thanks a lot for your help!

 

Chris