TheOubliette , 11 hours ago

I would recommend using this as an opportunity to build out and use a backups system. Whenever I get a new laptop, for example, I just make a(nother) backup on the old laptop and restore whatever I want to the new one. If there are any files I want that are normally excluded from backups, I either tweak my rules to include those files/put them in a different directory and repeat the process or just make a new manual external backup copy temporarily.

If you have good backups then your new drive can be populated from them after creating new partitions. Optionally, you can also take this opportunity to reinstall the OS, which I personally prefer to do because it tends to clean up cruft.

Also, if you go this route, your data on your old drive is 100% intact throughout the process. You can verify and re-verify that all the files you want are backed up + restored properly before finally formatting the old drive for use in the NAS.