Dear support,

I have a problem with a replacing of a HDD to a SSD.
My Unraid system tels me that the drives are not the same size.
But when I check on the system via terminal.
root@void-unraid:~# blockdev --getsize64 /dev/sdf

4000787030016
They are the same.

ChatGPT tels me to use "New Config" to populate the array for "New". But the text in "New Config" is so vage that I don't dare using it.
See the screenshot for my disk config.
Can someone explain the "New Config" stuff?

Edited November 12, 2025Nov 12 by Kjeld
Added log and change topic with version prefix

New Config is a new drive layout basically. When you use this feature, the system "forgets" the drive layout (where each drive belongs), so like the info page says it's effectively like setting up a new server. The understandably confusing part is that unlike an actual new server, your drives have data in them and to make it clear, said data is not touched by this process, this is only a configuration change.

From what I gather, you are probably trying to replace the drive so then it can rebuild to the new drive with the data the WDH0E9CB drive had. That being correct, New Config is not really what you are looking for since that invalidates your existing parity data.

If you exhausted all the disk replacement suggestions and the drive simply refuses to be assigned to the desired slot with the existing config, New Config can be an option but you first you would manually have to transfer all the data over from the drive you are replacing to the one you are replacing it with (ensuring all the array data is present in the data drives before new parity data is calculated). Then you could do New Config, assign the drives to their previous roles (as they appear in this screenshot), start the array and it should rebuild the parity data. Of course, this assumes the old drive works.

I am going to make a drive copy.

If the data is the same on the drive will the settings for Untaid like Docker images and VMs also stay working after this?

Also thanks for helping.

You cannot replace an HDD with a SSD of the same capacity, since Unraid uses a slightly smaller partition for SSDs. This is for performance reasons, so it needs to be replaced with another HDD or a larger SSD.

If that's not a good option, you could mount the SSD outside the array, copy all the data from the emulated disk there, then do a new config with the SSD and resync parity.

Also note that SSDs in the array are not recommended, since TRIM won't work.

Thanks for the help all.
I ended u useing "New Config" with my old drives.
The new SSD's crashed during calculating from parity to a new drive.
So I had two broken SSD's. I popped in the original HDD's in teh correct order and did the new config.
Its doin parity calc a swe speak. So I am never going to use SSD's and don't recomend anyone doing it.

I kept my head clear and did not panic and kept te original drives, so crisis averted.