diskDedupe App Reviews

Great for deduplication on APFS

This utility is extremely fast and flexible. Unlike other duplicate file finders, this one has a few unique features including: ability to scan only files above or below a minimum size, and a simplified deduplication process that doesn't require you to pick a canonical original. Under the hood, the speed comes from the APFS file cloning capability, which is sort of like really efficient hardlinks on HFS but allows copies to diverge efficiently without clobbering one copy or the other if a cloned copy is modified or deleted. This takes the guesswork out of deduplication, and for its use case beats the pants off of any other duplicate file utility I know of. The only real limitation of this utility is that it ONLY works on APFS file systems. You can't use it on HFS disks. However, it *does* work reliably on mounted APFS disk *images* (including sparsebundles) even if they're located on HFS or other filesystems, so it's a great way to get the benefits of APFS cloning and deduplication even if you have spinning disks or RAID systems that don't do APFS well. One sparsebundle was reduced from 9 TB to only 1.4 TB after deduplication with this utility followed by hdiutil compaction. Your data patterns may vary, but this was pretty compelling for me. In short, I highly recommend it.

Like Magic

If there's any other app that uses clones to dedupe your system, I'm not aware of it. I think this is the only one. The user interface is a little bit confusing, but not taking away any stars. It should have a reasonable default starting folder (user home folder) and a better default miminum file size to mimimize deduping many small files. The user can change those settings, but they should be default.

Excellent and efficient

It does what it says it does. It finds duplicate files and combines them so you don't use storage you don't need to. It uses something called "hard links" which have multiple file pointers pointing to the same data. Backup before you do it, but I haven't had any problems using it and because many of my files and photos were duplicates, it's saved a lot of space. I wish it were a little faster, but I have a lot of files! Maybe it could use the APFS FileVault file hashes instead of calculating them on its own.

Crashed everytime I've tried to use it

Bought a 16tb to drive to combine 3 x 4 tb worth of data and then dedupe, however after running this for nearly a week solid, it's crashed my computer each time after either 1 or 2 days or running. It's also not been updated in over a year, I guess it's not stable on Monterey. I'll try a few more times but restrict the file size to reduce the runtime and if that doesn't work then I'll get my money back from apple.

Great app!

This app works perfectly! I would only advise against using it on files in iCloud Drive, because iCloud Drive storage acts differently than any other "normal" APFS drive. When I used it on iCloud Drive, iCloud preserved all of the original files I "deduplicated", as well as all of the copy-on-write duplicates that this app created, so I essentially ended up with two copies of each of the files (the original plus the new copy-on-write file). Other than that, the app works great on any APFS drive I've tested it on!

Downloading more RAM but for disk space

I don't pretend to quite clock what this app is really doing, but I know that it's some APFS magic that I really enjoy. This is a nice little utility like Monolingual or ImageOptim that makes you feel like your computing life is just that bit more optimized and less wasteful.

Great app. One niggling concern/request...

I nearly gave this only 4 stars, kinda wanting to give it maybe 4.5, just not quite 5. But maybe 5, with a "but..." is close enough... It seems to be the most reliable and fastest "dupes to clones" app I've been able to find. I've so far only run it on data I could afford to lose in a pinch if it screwed things up -- mostly old archives of stuff I probably don't really need but just don't want to throw away just in case. Haven't found any problems yet, although I've only opened (to test) a tiny fraction of what it's processed. Still, so far so good. Also, from what I can tell -- well, at least, assuming what it's reporting to me is accurate -- it compares files a number of "shallow" ways (filename, size, etc.) and disqualifies anything that doesn't exact match through those methods, then hashes anything that might still be a match, to make a final decision. (Developer/author, please correct me if I've got this wrong at all). Assuming that's what it does, then the end result should be (and so far seems to be) completely transparent (ie. before == after) except for a bunch of newly saved disk space. In short, so far, it seems to do exactly what it says on the tin, and has proven to be the (almost) perfect solution to a particular problem I needed solved. All that said, I feel like it really needs just a little more functionality and UI. Specifically it's kind of all-or-nothing. Well... it lets me choose a folder rather than a whole drive, so some selectivity there. But a little more flexibiltiy would be great also. Specifically, something like this: it presents in the log a very clear to understand list of all the dupes it's found. If it could present that list in the UI, each row with a checkbox to say "ok yes, replace this file with a clone" vs "no, leave this one alone, don't replace it with any clone, don't touch it in any way". Then again, this might not even be the right solution to the problem I'm really trying to address, that is: just hitting a "Deduplicate" button and letting it do its thing requires an awful lot of trust, especially on potentially irreplaceable data. Not security or privacy type trust, just trust that it really is doing what it says its doing and there isn't some bug that might destroy some of my data. Perhaps, for example, is the "no collision" thing absolutely guaranteed? I guess I'm not really sure what the best solution to that is. I put a lot of the same kind of trust in my backup apps, but then again I back up my data three different ways with three different apps, so if one of them destroys my data or fails in some way I've got the others. In some sense that applies here also, so maybe that's good enough. But I think the above extra UI (the list with ability to uncheck some items) would still be a really good option to add.

Doesn't do what I bought it for

I paid for this app for the specific purpose of cloning the internal drive of my Mac Mini to an external SSD in preparation for replacing the Mini's internal drive with the SSD. But this app doesn't do that. I misread the description so this is my fault. That said, the developer is first rate with a personal response and kind, helpful suggestions for getting a refund. In fact, I may well keep this app just for the excellent support...

Works well for reasonably-sized sets of files

This works well when scanning reasonable amounts of files, up to a few million at least — it saves space and seems to be reliable. It’s cleaner and generally much faster than script-based solutions. The interface is bare-bones but easy to use. However, I tried applying it to a much larger set (60 million files) and its memory requirements grew to 90 GB by the time I gave up 20 hours or so later (due to needing to actually use some of those files, and memory swapping eating into the SSD lifetime on my Fusion drive). A .dedupCache file is created; is this used to avoid processing duplicate files again when rescanning? There’s scant documentation.

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