Carbon Copy Cloner - Source drive lost 40GB after first backup

[pinkoos]

So, in reference to the ongoing saga of migrating my old Mac to my new Mac, I finally got that part done last night.

Out of my 500GB SSD, I had about 155GB available.

I setup the first CCC backup to run overnight which it did successfully.

However, after the backup was performed, the amount available on my source SSD dropped from 155GB or so to 111GB or so.

So, in summary, without having done anything except run the initial first CCC backup, the source SSD lost about 40GB of space.

What gives?

 

[amaze1499]

deleted

 

[pinkoos]

Not sure what you're asking - just did a simple backup and lost 40GB of space on the source drive.

 

[BrianBaughn]

Disregarding CCC, on the source Mac do you use Time Machine or another automatic backup service?

 

[pinkoos]

I had used Time Machine on the old Mac and then used Migration Assistant to migrate my accounts and data to the new Mac, but made a point not to set up Time Machine on the new Mac (for various reasons).

 

[Fishrrman]

I'm going to -guess- (and it's ONLY "a guess") that in creating the clone, CCC ignored a bunch of Time Machine "local snapshots", and "local backups", or whatever they call them.

My advice:
Boot from your cloned backup.
Open it up, and "take a good look around".
Is everything that you expect to see there.... there?

If so, CCC did what it's supposed to do, leaving "the TM cruft" behind.

I've never used TM.
I've even gone so far as to REMOVE IT from the applications folder, and delete the TM preference pane as well.
I don't want it around!

 

[pinkoos]

So I was in touch with Mike at CCC and was able to send him my logs. Turns out it's very common for Finder to mis-report disk space values. He said that a lot of times, the Finder is just blatantly wrong.

He provided some links for me to read and videos to watch, which I will try and get to this evening.

So, when my backup started, I actually had 112GB free and when it ended, I had 111.5GB free (he said that is normal).

 

[treekram]

There are ephemeral files that only make sense to the specific computer at the the specific time it was being used. Probably the ones that take the most space would be a virtual memory file (stored on a separate volume if you use APFS) and the sleep image file - but there can be many others. So the use of the word "clone" is not quite correct. If you want a perfect clone, you'd have to unmount both the source and destination drives (so you'd have to have a 3rd disk to boot from) and do a complete byte-by-byte copy - which is slow and cannot be done on an incremental basis.

 

[poorcody]

So I was in touch with Mike at CCC and was able to send him my logs. Turns out it's very common for Finder to mis-report disk space values. He said that a lot of times, the Finder is just blatantly wrong.

CCC has really good support... I actually go to their support documents first when I have general questions about any disk issues...

https://bombich.com/kb/ccc5