I have yet to see a fragmented file completely recovered by Photorec (perhaps it works sometimes on a memory card, but on a large HDD the odds are very slim, as fragments can be located anywhere, not necessarily at the next free space, it can be 1TB further, or 1TB before the beginning, totally impossible to guess, the program has to be aware of the structure of each file type at a very deep level, which Photorec is obviously not). It's still very good at what it does, especially for a freeware, but it still has issues : indeed it can be excruciatingly slow because of that nearly hopeless fragment searching (it doesn't seem to be caused by a heavy CPU computation, rather, the algorithm seems to be reading hundreds of GB over and over again whenever it finds a seemingly incomplete file, which seems very inefficient) ; it can generate a lot of false positives, especially for JPG and MP3 files which are seemingly identified by a 3 bytes signature only, in which case the file that came before, containing that false signature, is either truncated, or cut and merged with what comes after the end of the identified fake file, making the former file partially or totally unreadable, even if that file was still complete and contiguous on the source device ; it can extract humongous files, with totally unrealistic sizes, like 2GB DOC or XLS documents or 160GB ISO images (enabling only a few file types reduces the amount of false positives but increases the likelihood of those gigantic files : after doing an analysis of a 3TB drive and finding all those fake JPG / MP3 and all those truncated video files, I made a second analysis, enabling only AVI, WMV, MP4, MKV and ISO -- not MPG because some ISOs contained MPG videos, and
MPG are themselves very problematic with regards to raw recovery, -- this time all non-fragmented video files were completely extracted -- especially a quite large number of MKV files which were no longer referenced, while
raw recovery of MKVs was then very poor in R-Studio -- but I got a 160GB and a 85GB ISO files, although both corresponded to much smaller ISO files, which were still referenced and not fragmented).
I reported those findings on the dedicated forum a few months ago, but the only reply I got was rather cold... (I got a reply from the author more recently, when reporting a more specific issue with
MP3 files which have a double ID3 header.)
As for
Klennet Carver, and CnW Recovery, haven't tried them, they seem to be very different kinds of beasts, with a much more sophisticated approach.
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