I'm pre-clearing a couple 6TB drives that I will use to upgrade my parity drive and add more storage to my array. I'd also like to transfer the current parity drive to the array as a storage drive.

 

Is there any problem with doing at all at one time by creating a new config? Parity needs to be recalculated anyway, so I thought I'd cut down on unprotected time by doing it only once. I've read about people changing the parity drive first, recalculating parity, then adding the old parity drive to the array and recalculating. If I were to do just do one drive at a time then wouldn't I have to go through three parity recalculations and have three days or so of being unprotected? Is that really necessary?

 

Thanks!

Actually, if you were to add the old parity drive without doing new config then it would have to be cleared.

 

I don't see any reason why your plan wouldn't work. The old parity drive will be unformatted, but with a new config it won't matter if it isn't clear.

 

Might wait for someone else to confirm this though, since I haven't done it that way. Not sure exactly what unRAID will do with a new config that has an unformatted drive.

I'm pre-clearing a couple 6TB drives that I will use to upgrade my parity drive and add more storage to my array. I'd also like to transfer the current parity drive to the array as a storage drive.

 

Is there any problem with doing at all at one time by creating a new config? Parity needs to be recalculated anyway, so I thought I'd cut down on unprotected time by doing it only once. I've read about people changing the parity drive first, recalculating parity, then adding the old parity drive to the array and recalculating. If I were to do just do one drive at a time then wouldn't I have to go through three parity recalculations and have three days or so of being unprotected? Is that really necessary?

 

Thanks!

 

If you take the time to preclear the old parity drive after you remove it from thje array, it will be added back into the array in a matter of minutes.  Of course, you will have already added the two new 6TB drives to the array and the array will be protected as soon as the parity sync is completed for that operation.

bjp999 has advocated the approach you mentioned in several threads. Here is one example. Note that it is not necessary to clear the old parity drive to add it as a data drive in a new config if you wait to format it until after parity is built.

 

You might PM bjp999 and point him to this thread for confirmation.

If you only change the parity and let the parity build on the new disk then you can revert to the old array state to recover if another drive did fail. You have to not write to the array and keep the old parity drive intact until the parity build is complete.

 

Precleared drives add quickly in a matter of without any parity building. If you don't preclear them then unRAID will clear them itself and the array won't be accessible while the drive is being cleared. In either case,  you are never without parity protection during the process. The clearing is how the parity is maintained.

 

The only real advantage of doing the new config would be avoiding having to preclear the old parity drive.

Thanks everyone. I forgot that new cleared drives could be added to the array so quickly and without rebuilding parity. I think I will take the approach suggested by lionelhutz.

 

Secondary question: preclearing 6TB drives takes a LONG time. Is it necessary to do two passes? Or can I stop it after the first pass completes? I had hoped to get this done before going out of town, but the preclear is taking about 90 hours per pass.

The 6TB drives are still very new.  I personally was very cautious with mine an precleared them both 5 times.  Especially when the first one arrived DOA.  If its going to fail, I want it to fail now.  I ran a 1/2/2 cycle.