If say my array is 20TB and I add a new drive increasing it to 25TB, am I able to remove that drive from the array reducing it again to 20TB if no files were written to the new drive? is this possible in the 6.2b release?

I'm guessing as long as I have my disk layout documented, I could just do a new config and everything would go back to the way it was?

If you remove a formatted disk from a parity array you will have to rebuild parity. A formatted disk is not a clear disk. Even without files a formatted disk has a filesystem on it.

I recall a discussion about a feature request to allow a disk to be removed without invalidating parity - which involved a process very similar to clearing it in situ (actually, clearing the associated /dev/mdX). The procedure was worked out but hasn't been implemented as a core unRAID function.

 

 

EDIT: Here: http://lime-technology.com/forum/index.php?topic=30270.0

Its actually doing a clear now, not sure why, I just added it by stopping and starting the array. Is it normal for it to do a clear before adding it to the array?

Its actually doing a clear now, not sure why, I just added it by stopping and starting the array. Is it normal for it to do a clear before adding it to the array?

It must be clear to keep parity valid. Same reason why you can't remove it without redoing parity unless it's clear.

Its actually doing a clear now, not sure why, I just added it by stopping and starting the array. Is it normal for it to do a clear before adding it to the array?

 

Yes, that's normal.  In fact, with previous versions of UnRAID, the array would not be available during the clearing operation -- that was in fact the primary reason the pre-clear utility was developed many years ago.    With the latest release, this isn't an issue, as UnRAID automatically does a clear; and THEN updates the array with the new disk.

 

As for removing it => simple answer is you can't do that.    More complex answer is it's possible, but only with some gyrations that involve writing all zeroes to the drive; then doing a New Config and checking the "parity is already valid" box.

 

Best way to remove a drive (or drives) is to do a New Config, and simply assign only the drives you still want in the array.    This will require s new parity sync (thus your array will be unprotected and "at risk" for the length of the new sync) => so be CERTAIN that all is well before doing that [i.e. run a parity check and resolve any issues BEFORE you do the new config].