Available space on external drives according to Finder

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After running a scheduled daily back up scheme on CCC for a couple of years I decided to start a new scheduled back up scheme following the upgrade to Mojave. Prior to this the available space on my 1TB Thunderbolt external drive had reduced to about 450GB, which was due, in the main, to all the safety-nets it contained.

I am now using the same 1TB thunderbolt drive, now formatted APFS, and a quick look in Finder at that drives contents showed I have 928.49GB available, which seemed a **** of a lot to me, so I checked what CCC indicated and that was 858.61GB and that seemed about right. The CCC figure was confirmed by Disk Utility as 858.61GB.

Out of interest I checked out the, separate, APFS external drive I use for Time Machine and according to Finder 269.22GB was available but according to CCC and Disk Utility it was only 224.74GB.

Not the end of the world BUT where the **** is Finder getting the extra GBs from?
 

chscag

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Sure sounds like something is out of whack there. A difference of around 45 GB is a huge error if that's what it is. Did you try a reboot and check again with Disk Utility?
 
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Could it be snapshots taking up that space? You can read about CCC snapshots at the Bombich website. He also talks about Time Machine snapshots, so you can sort of figure out what the relationship between them may be. I ended up turning off CCC snapshots and now everything matches on space available (and I have a lot more space now than I did).
 
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I think I'm getting to grips with this issue - maybe!

Using Disk Utility to examine my CCC back up drive the bar at the top of the screen shows that 857.97GB is Free but at the bottom of that screen it shows that 928.43GB is Available, which is what is shown in Finder.
Using CCC to examine the same drive shows that 857.97GB is Free.

Disk Utility & CCC both appear to suggest that what is Free space may not necessarily be Available for use??

Maybe (purgeable) is important?

CCC Back Up Drive.png
 
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Disk Utility & CCC both appear to suggest that what is Free space may not necessarily be Available for use??


I was just wondering if the difference could possibly be due to TRIM or some garbage collection not having the storage area ready for new data to be written, but that's sure not going to be happening with the Toshiba MQ01ABD 2.5-inch 5,400 rpm HDD that seems to be in use.

So, back to the drawing board and think tank I guess!! At least there's approximately 70GB Space available — I guess. Give or take a few GBs maybe.





- Patrick
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Thanks for your interest.

Just out of interest I plugged in a different external drive that was formatted ExFAT. This was a 1TB drive and contained an 11.28GB folder of photos. According to Finder it had 1.04TB of space still available!! Disk Utility indicated that 988.84GB was Free and Available.

I guess it'll end up as one of lifes little mysteries and, hopefully, won't be a problem as, whatever the space is that is left is unlikely to be all used up by me!

Thanks again.
 
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I guess it'll end up as one of lifes little mysteries and, hopefully, won't be a problem as, whatever the space is that is left is unlikely to be all used up by me!


Did this little "feature" just start with your recent Mojave install???





- Patrick
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Ahhhh well the simple answer is that I haven't got a clue really.

I do remember looking at the available space with previous operating systems on Finder for both external drives as it got smaller and smaller and looking forward to seeing how each bit of software dealt with the lack of space BUT, and there's always a BUT, I don't ever remember comparing Finders indication with that of Disk Utility.

I suppose I could always use all the back ups I've got to completely reinstall High Sierra too precicely how it was before Mojave and have a look at it but, then again, maybe not;-)
 
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Further research reveals that the space that aopears to be missing in DiskUtility is 'Purgeable' space, which has something to do with using cloud storage and optimising the disks. If you fill up the disk beyond it's apparant capacity it will release some of the 'Purgable' space by utilising cloud storage. I think that 'Snapshots' are involved in this as well somehow. Anyway it's not a problem that can't be solved with a stiff Gin & Tonic, plenty of ice and a slice of lime!
 
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Anyway it's not a problem that can't be solved with a stiff Gin & Tonic, plenty of ice and a slice of lime!


And don't forget a drop or two of Angostura bitters!!! Or more. :Smirk:





- Patrick
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