First thing I’ve learned is do NOT trust the Finder in any way when looking at one’s whole disk. Just one example, yesterday it said I had 838G used. Today it says 614. When it said that 800G number I did a GetInfo on each of the 4 main folders… that aggregated to about 650ish. Today it’s down the 614. Someone said to never trust the Finder and look at disk Utility, it will tell the truth. Well, today I see it verifying the 614G figure. Crazy.
So I went lookin g for some app that I can drill in to my stuff to see what takes up what size. Tried a few but the only one that seems to come close to what I am looking for is Disk Space Analyzer. So the question is, is that reliable? Is it the choice of others? What might be better? The one quibble I have is it shows what’s available, but not the total on any specific disk. It seems to use the Finder’s suspect calculation of what is taking up space on a volume.
Longtime Mac users often get caught up in looking at the amount of free space reported by the Finder. We’ll check the storage numbers shown in a Get Info dialog, delete something, and check again. Don’t waste your time! Space management on the Mac is now largely indeterminate thanks to APFS, Time Machine snapshots, purgeable space, and more, as Howard Oakley explains. These technologies render the Finder-reported number unreliable at any given point in time. Even after you empty the Trash, it may take macOS several hours or more to update its free space reports. Restarting may or may not help trigger a recalculation.
Thanks Adam, this whole issue had me flummoxed… now I have some stuff to read and hopefully digest. I’m less than a week going from HS to SEQ and am noticing too many issues that are really sucking up my time to figure out (and a lot of simply bugs, what should work, but do not).
DaisyDisk is, almost universally, considered the best. And at US$10 is modestly priced. For the system disk, it is important to “Scan as Administrator” to get some level of detail with system and “hidden” files.
Seems there is no “try it out for a week” or anything like that, so it’s hard to pass judgement. BUT the screenshots looks very similar to the one I have, Disk Space Analyzer. Even circular graphs. I can stop it from showing then get a multi-column view as I click on folders. They have a Pro version for money, but am not sure how much I need that… it’s 10 bucks/year. Oh the Pro version can delete stuff.
Ooops, my bad, I ws only looking at the app store, went to their webpage and I got a try out.
Another vote for DaisyDisk. Do not be put off by the (IMO) useless graphic chart, but concentrate of the numbers at top right. It is fast and also reports local snapshots and purgeable space. I have tried all the others of this type at one time or another.
Howard Oakley writes plenty on Finder issues. Here is one link that relates to this topic, possibly not most up to date but hopefully a helpful starting point:
Here is an example of Finder stupidness. This is a screenshot of Finder’s ‘Get Info’ window for the internal 1 TB SSD of my new M4 Mac mini, macOS Sequoia 15.2. It says:
Capacity: 994.66 GB
Available: 1.3 TB (415.47 GB purgeable)
Used: 98.27 GB on disk
(Also, the bottom of any Finder window displayed “1.3 TB free”)
How can a 1 TB disk have “1.3 TB” free space? (That’s physically impossible!)
On Thursday, I tried to clean up an external backup hard disk, so I copied (using Finder’s copying) more than 400 GB of its contents over to the internal SSD, then reformat the external disk, then copied the 400 GB amount back to the external disk, and then deleted the 400 GB data from the internal SSD (moved to the Trash and then emptied the Trash.) After that, Finder’s ‘Get Info’ window showed:
Capacity: 994.66 GB
Available: 899.05 GB (415.4 GB purgeable)
Used: 502.88 GB on disk
which stayed at least for 24 hours; then it suddenly switched to the above craziness (“1.3 TB free”) that stayed at least for another 10 hours; and then it has returned normal now:
Capacity: 994.66 GB
Available: 892.28 GB (4.56 GB purgeable)
Used: 98.81 GB on disk
Since Carbon Copy Cloner (data only) backup on an external SSD says “Used: 73.16 GB”, this one is a believable number. System Settings > General > Storage says “893.01 GB free”, which is close enough, too.
So, my Finder was hallucinating of having “1.3 TB free” just for 10 hours.
Just a random guess, but I’d guess that the Finder is naïvely adding up the sizes of all those “purgeable” files (that is, those that can be auto-deleted to make space) and is not considering the possibility that:
Those files may be hard-links. That is, multiple directory entries pointing to the same file. The sizes shouldn’t be double-counted, but maybe the Finder got it wrong.
There may be sparse files, where unused (zero) disk blocks don’t consume any storage. The sizes should be the size of the blocks used, not the total file size, but again, maybe the Finder got it wrong.
If you double-count or mis-count the size of the purgeable files and then add that to the actual free space (e.g. what Disk Utility reports), that would explain the crazy numbers.
This not a new problem* nor one confined to APFS formats. Here is a screen shot of Get Info on a camera storage card (SDXC) formatted in ExFAT. It has a capacity of 64 GB but Finder reports 84 GB available and 20.55 GB purgeable even though only 9 MB are used.
Disk Utility and the /bin/df command both show correct values.
Gotta write CCC/Mike, Finder reports way wrong for my eternal CCC backup… but Omni Sweeper reports something close to what the Finder says despite the fact adding up the folders on that drive amount to something far smaller. Which may be a snapshot issue, I replace a 100G folder of one thing with a 100G folder of another thing. As I understand it, ussing a snapshot can get me back that original 100G file… is there some hidden space on my CCC backup stuff like this may be stored?
