cgsecurity.org

I've had PhotoRec running for a few weeks now, and it's about half way through the number of sectors. It has found over a million files, so that's good, 2.7TBs worth so far. However, the time to complete is just going up and up and it seems to be getting slower and slower. Initially it was finding thousands of files every day, but in the past week it's hardly finding any each day. Is this to be expected or should I stop and start it again, and on that note can I start it from where it left off? (I can probably find that out from the documentation, tbh). Maybe the log file is too big or it's just struggling with the size of the volume.
Also, the disks a running at ~50 'C, which is at the top of their operating range, maybe that's not helping?

Checking the SMART status of every member disk, and if necessary duplicating the whole array frees PhotoRec from dealing with broken sectors.

Physically healthy disks don't cause a slowdown. PhotoRec can be interrupted and restarted but I don't know how it behaves during a restart on a duplicated RAID array.