Hi @Welcome, Martyn
It's always much more difficult to solve a similar problem "after the fact", that's quite right.
Just note that if I had to give some advice "before the fact", that would include:
- don't use a NAS for storing your pictures and catalog databases. The reason is I am not competent... Adobe will not support NAS issues and successful NAS users never come here to help their friends. Use your NAS instead for backups, for instance.
- Just like Lightroom users, ignore the default storing of your pictures in the default Windows 'Pictures' system folder. Ideally store them on your own master folder directly under the root drive of an external or internal drive (or a new partition).
- It's good to have another backup solution than the integrated one in the organizer for both your pictures trees and your catalog folders. I believe that's what you have now. You are not sure to restore your library with no 'disconnected' files, but that may help.
I don't understand precisely your project but I have a feeling it will fail to reconnect. As you have already read, your catalog stores the location of your media files by identifying the internal Windows serial number for the drive as well as the full folder path on that drive. I believe that choice was absolutely necessary to distinguish between removable media like CD/DVDs as well as to provide a solution for the way Windows attributes drive letters. This allows recognizing a drive even if Windows has attributed the same letter to another device inbetween (not guaranteed...)
The major drawback is that nobody knows how to get that serial number. To get it, you have to start a DOS command (execute / cmd) wich opens a text window in which you type:
Vol X:
for the X drive for instance.
The serial is returned in hexadecimal form.
You can translate that hexadecimal number into decimal with the 'Calc' tool in programmer mode.
Advanced users familiar to the Sqlite database management can open the main database 'catalog.pse19db' and look at the volume_table which shows the recognized drives by the catalog with their properties. They can find the record for the drive with its properties from the initial drive letter. They can assign the properties of the new drive (letter, serial, type...) to replace the old ones, without changing the internal identification of the drive by the database. That only requires knowing the serial number of the new drive.
I use this myself instead of backup and restore betwen several drives. I use a fast Microsoft Synctoy utility to sync my folders tree between two drives. A few minutes instead of three hours backup and as many for the restore. Then a couple of minutes and I am ready with the updated catalog on the new drive.
And for most PSE users not acquainted with sql language?
A possible solution can be tried from this help file for the psdbtool created by John R Ellis:
psedbtool (Photoshop Elements Database Tool)
scroll down to:
Change a Drive’s Volume Serial Number
So, if you have an exact copy of your library on a different drive and you know the new serial number, you can make the organizer recognize the new drive instead of the old one. However, you should not have two drives with the same serial at the same time. That's one more reason to store your library on a different drive than your (C:) system drive.
Special notes on cloning drives.
If your library is on a different drive, the clone will work just like the original. Cloning will keep the serial number.
However, it's increasingly common to replace a classical drive for your system (C:) drive with a cloned SSD. If your pictures are on (C:) and the SSD is big enough to hold your whole library, OK. If it's too small and you want to use the original (C:) drive under a new letter your catalog will see two distinct drives with the same serial and the catalog will be corrupted. Better to move your photofiles to a different drive before replacing the system drive with the SSD. If you have a correct backup, you'll be able to move the catalog and library normally. Another good reason to keep them on a different drive than the system one.
Tip for advanced users knowing sql: if you have no idea of the serial number of the unavailable old drive, it's in the volume_table if you have a copy of the catalog folder, even an old one. Let's say you want to edit a copy of your catalog dabatase for a drive to work with another drive. Locate the original drive from its letter. If the new drive is already in the table under another letter, you can check by its serial and delete the whole record. Then you change the properties (mainly the serial and letter) in the old record. That's all.