Can't Copy File to External SSD

[Godel_I]

My MacStudio has a 2 TB internal drive, and there is currently ~700 GB used and ~1.3 TB free. I'm trying to copy a file of ~650 GB from the internal drive to an external 1 GB SSD. Each time the copy is prepared, I receive an error message asking me to free additional space (~5 GB) on the internal drive to copy the file.

What am I missing?

 

[BrianBaughn]

It seems with a big file like that macOS needs twice the amount on the source disk. Assuming the message is correct about the 5GB the easiest thing would be to clear that space. Perhaps you have something that large that you could copy to the external and then delete on the internal…then copy it back when the 650GB file is done.

There are other things to try and this website offers some suggestions:

Error: Not Enough Disk Space to Copy on Mac (USB)? Fixed

Fix errors like 'Not enough disk space to copy' on Mac & 'The item can't be copied because there isn't enough free space.' on Mac. Understand why Mac says not enough space when there is.

iboysoft.com

Since I have Carbon Copy Cloner I'd probably try that.

Maybe someone knows of a Terminal command that can do it.

 

[FreakinEurekan]

When something like this pops up, I start by assuming "There is a reason for it" and I do what the dialogue suggests.

If you want to just copy the file - delete the 5GB.

If you want to know WHY it's happening, let's start with the file type (is it a single file, or perhaps a "Container"?) and the format of the external disk (exFAT, APFS, Mac OS Extended, etc)

 

[Fishrrman]

I believe CarbonCopyCloner might be able to succeed here, where the finder fails.

CCC is FREE to download and use for 30 days.
This means that if the OP is not already a CCC user, he can get this task done without paying for a full CCC registration.

WHAT WILL NEED TO BE DONE:
The OP will need to set up the internal to backup to the target drive,
HOWEVER...
Before starting, he will need to go into the "task manager" window and UNCHECK EVERYTHING, EXCEPT the individual file that will be copied.
This will take a little time, but needs to be done.

The OP will also have to open CCC's preferences, and UNcheck the option to create a snapshot.

Then proceed with the copy.

I have to ask:
What kind of file is 650gb in size?

 

[Ben J.]

The CCC procedure would be:
Install CCC
Launch CCC from the menu bar item
Create a new task
Set the source to be the file or folder
Set the destination to be the external disk
Run task