Well, for the second time in my life I managed to blow away a partition by accident. In the process of trying to convert my two 1TB internal drives into a RAID0 volume, I accidentally destroyed the partition table on our 2TB external disk, our "backup drive". It turns out Windows' "Storage Spaces" is more than happy to destroy the partition table on an external drive before determining it can't use an external drive for said purposes. Whoops. Side note: I found "Storage Spaces" to be wholly useless, and used the disk management console the same way I did way back in NT4. Anyway, the external "backup drive".
Ironically, some of the data on there was the only copy of that data, which really didn't make it a "backup" at all. There's a quote out there somewhere about the number of backups always being one less than the number you think you have.
After searching for a bit for a program to do the job, and finding nothing but trialware trash, I stumbled upon the rather fantastic TestDisk. It took about 25 hours to examine the entire drive, at which point I fat fingered a menu option, and had to start the process over. After nearly 50 hours, I successfully recovered the partition table, rebuild the MBR, and... nothing. Windows sees it as a "raw" partition.
However, TestDisk was able to see the partition, and copy files across. So I built partitions back on the 1TB drives, and copied the data across. The process went rather quick (close to 200MB/s), but it still took a while to complete.
After that, I reformatted the external drive, and moved the data back. I then unplugged it before building my RAID0 volume, which I'm pretty impressed with. I lost data due to a hard drive failure back in the aforementioned NT4 days, so I'm not storing anything on it that's irreplaceable. I'm putting the larger of my Steam games, downloads, and that sort of thing on it. In a not-terribly-scientific stopwatch test, GTA5 takes 1:27 to go from clicking "play" in Steam, to the single player campaign on an SSD. It takes 1:34 on the RAID0, a whopping seven seconds longer. The results are decidedly unscientific (there's a cloudsave sync in there, and I have to click "story mode" in the middle which I tried to do instantly but there may be a deviation still), but I think I can live with that.