Hey there! I've been running unRAID for some years now and have been getting better at administration, but, as I'm maxed out on power and space in my case I'm at a bit of a conundrum.

I have a 7-drive system (6+array) with a 14TB parity and I just picked up a very good (shucked) deal on a 26TB Seagate drive so I'm looking to, ultimately, replace my smallest drive (4TB) with the parity and replace the parity with the 26TB. Unfortunately I don't have physical space/power to install the 26TB drive alongside the 4 and 14TB one, so I need to come up with a plan to remove/bypass it. Also, since I don't seem to have any external USB connections which'll let me preclear the new drive without plugging it into SATA, I'm at a bit of an impasse.

I've already moved all the files off of and removed the 4TB drive and put the 26TB drive in its (physical) place and am currently zeroing the drive with preclear. unRAID is 'emulating' the 4TB drive, but there's no data on it, so that's of limited concern except for parity. So...my question is:

Once the pre-clear finishes, can I stop the array, throw the 26TB drive in the parity slot and move the parity into the (currently emulated) place of the 4TB drive, start things up, and be fine? Or, as my gut wants to tell me, do I need to do this in stages: going parity-less for a stop/start when I move the parity drive to the array, restart the array, then add the 26TB drive to be parity. I guess this'll be my default unless someone weighs in confirming I can do both at once...

You can use the parity swap procedure

According to that it'll be down for 'many hours' while it copies parity? With a 14TB old and 26TB new parity drive i imagine that'll actually be days. I don't mind going without parity while it rebuilds, but can I skip that long copy procedure?

You can also just upgrade parity first, power down, replace the old parity with the new one, resync parity, and when that's done, replace the other data disk.

Since i didn't have enough room in my case, though, I had to remove the smallest (array) drive before installing the newer 26TB drive, so right now I'm sat with the array emulating that drive despite the fact i completely emptied it. Will it be ok for me to just stop the array and replace the parity and start it again, allowing it to rebuild parity even with that emulated/missing array drive?

I suppose another option could be for me to simply create a new config with that empty drive removed, but I'm a bit nervous about that if I don't need to go that route

1 minute ago, polishprocessors said:

so right now I'm sat with the array emulating that drive despite the fact i completely emptied it.

In that case, only the parity swap procedure can help, or

1 minute ago, polishprocessors said:

suppose another option could be for me to simply create a new config with that empty drive removed,

Ok, then one more question: if I create a new config, how high is the risk of losing data? There's absolutely nothing on the removed 4TB drive, so nothing's being emulated. I guess my steps would be:

1) new config and rebuild parity without that drive

2) stop array, remove parity drive from config, start array

3) stop array, add new pre-cleared 26TB drive as parity

4) let parity rebuild

5) add 14TB drive back into array

6) let parity rebuild

Is there any way to compress any of those steps, or, if I want to leave my array running at all times except for the stop/starts, is this the path I need to take? Guess that was actually two questions...

Edited November 2, 2025Nov 2 by polishprocessors

Since there is nothing on the 4TB drive you want removed then using New Config gives you a much faster option with minimal downtime.

• Start with New Config and use the option to keep current assignments

• Change the parity drive to be the new 26 TGB one you want to use, and change the 4TB drive you want to remove to be the old 14TB parity drive

• Start the array to commit the new assignments and begin rebuilding parity. Unraid will not touch the data on the existing data drives. Note that until the parity rebuild completes you are not protected against another drive failing. The array is available during the parity rebuild although performance for accessing the data drives is degraded.

• Format the new 20TB drive to make it ready for use. This can be done while parity is being built if you want.

ok @itimpi just went through New Config, preserved settings, and looks like I'm back up, with parity check running now and will be done in a day or two. Thanks for this-I'm always nervous to do anything this dramatic with my unRAID server, but it needed to happen so I'm glad it's finally working!