(of course when I try them individually I add / remove the # as needed. )
If anyone can assist me with what I need to put in that would be much appreciated. I've used:
/dev/big/bigger /home btrfs
in Ubuntu before and it worked, not sure what the issue is here.
That means you haven’t migrated your @home subvolume there which explains why you are failing to mount it. It doesn’t exist.
There are a couple of ways to solve this.
You can easily use snapshots and btrfs-send/btrfs-receive to migrate the existing @home subvol to the other drive.
Alternatively, you can create the @home subvol and manually migrate the data with rsync.
If you need instructions on how to do either of those let me know which you prefer. Although, you will have to wait 60 minutes or so since I will be away from my PC for a bit.
EDIT: Alternatively, if you already migrated the data a different way, then please share what you did.
This puts you home directory at the root of the btrfs volume. If that is what you want, then all you need to do is remove the subvol=@home from /etc/fstab. Something like this:
First of all, this is destructive so make sure you have the right things mounted or you could delete the wrong data. A backup is always a good plan as well.
To delete the subvolume you used to transfer, fist remount the root of /dev/big/bigger at /home2 again
Next you need to mount the root of the original disk(the one that held the old @home subvol you don't need anymore) somewhere if it isn't mounted already. It probably isn't mounted so I am going to assume you mounted it at /mnt/oldhome
Once it is mounted, you can delete the other copy of transfer snapshot and the original subvolume.
ID 256 gen 1532 top level 5 path @
ID 257 gen 1436 top level 5 path @home
ID 258 gen 1424 top level 5 path @root
ID 259 gen 35 top level 5 path @srv
ID 260 gen 1526 top level 5 path @cache
ID 261 gen 1532 top level 5 path @log
ID 262 gen 1520 top level 5 path @tmp
ID 272 gen 46 top level 5 path timeshift-btrfs/snapshots/2021-07-07_19-38-57/@
ID 292 gen 1426 top level 257 path @home/transferhome