What’s the best way to move 4TB of data from one hard drive to another?

[Christoffee]

Just drag and drop? In one go or in batches?

Make a CCC backup and let CCC do the work?

Are there concerns about data going missing or getting corrupted when doing a large transfer?

 

[rm5]

I think CCC is the most reliable way to copy data. If you want to ensure that everything is copied perfectly, use that. I mean there's no problem dragging and dropping (and it's something I do a LOT), but if you want like a super reliable transfer (for mission-critical data for example), use CCC. I think for your case, moving 4 TB of data, just use CCC.

 

[Christoffee]

I think CCC is the most reliable way to copy data. If you want to ensure that everything is copied perfectly, use that. I mean there's no problem dragging and dropping (and it's something I do a LOT), but if you want like a super reliable transfer (for mission-critical data for example), use CCC. I think for your case, moving 4 TB of data, just use CCC.

Perfect. Thank you.

 

[Fishrrman]

This way guarantees success (well, ok, 98% guaranteed):

Connect source drive (the drive you want to copy)
Connect target drive (the drive that's going to become the copy)

Open CCC.
Accept all CCC's defaults.

Put the source drive in "the box on the left".
Put the target drive in "the box in the middle".
IGNORE the box "on the right" -- not needed.

Then let CCC do its thing.

When done, the target drive will be indistinguishable from the source (except for the enclosure, of course!).

IMPORTANT PROVISO:
The above instructions are for "data drives" -- a drive that contains data only and IS NOT a bootable drive.
It's possible to use CCC to clone a boot drive, but if you're using Apple Silicon, it's now a different process.

 

[Christoffee]

This way guarantees success (well, ok, 98% guaranteed):

Connect source drive (the drive you want to copy)
Connect target drive (the drive that's going to become the copy)

Open CCC.
Accept all CCC's defaults.

Put the source drive in "the box on the left".
Put the target drive in "the box in the middle".
IGNORE the box "on the right" -- not needed.

Then let CCC do its thing.

When done, the target drive will be indistinguishable from the source (except for the enclosure, of course!).

IMPORTANT PROVISO:
The above instructions are for "data drives" -- a drive that contains data only and IS NOT a bootable drive.
It's possible to use CCC to clone a boot drive, but if you're using Apple Silicon, it's now a different process.

Thank you. It is just data. I think CCC seems to be the best option.

 

[okkibs]

You can just rsync the data over with the -a switch (a for archive), that preserves timestamps and everything. It's resumable if interrupted too. It copies on file system level, not on block level.

 

[Christoffee]

You can just rsync the data over with the -a switch (a for archive), that preserves timestamps and everything. It's resumable if interrupted too. It copies on file system level, not on block level.

Really interesting.

rsync Man Page - macOS - SS64.com

ss64.com

This?

 

[chown33]

Really interesting.

rsync Man Page - macOS - SS64.com

ss64.com

This?

I'm pretty sure that CCC runs rsync to do its copying. So if you use CCC, you're also using rsync.

 

[Brian33]

I'm pretty sure that CCC runs rsync to do its copying. So if you use CCC, you're also using rsync.

I was also under the impression that CCC used to use rsync to do its copying. But in the last year or so, they introduced a new file system copier, with more features like audit records. I am very curious to know whether the new copier also uses rsync, or not.

I have also noticed that if you use CCC to back up to a remote Mac, you must use the “legacy“ copier, which means you can’t use the new audit record feature. ☹️

I do love rsync, though. It is so reliable.

 

[Fishrrman]

OP:

You could also use SuperDuper.
As easy as it gets to use.
And... for your purposes... absolutely free.

 

[motulist]

Unless you need to do a special type of copy for a particular specific reason, you really don't need CCC or SuperDuper, you can simply just drag and drop the folder right in MacOS. If you really want to be completely sure that it all copied perfectly you can use a data-comparing app to check that the folders are bit-for-bit exact copies. But with that said, there's little to no downside to using superduper or ccc.

 

[okkibs]

If you really want to be completely sure that it all copied perfectly you can use a data-comparing app to check that the folders are bit-for-bit exact copies.

That's way more effort than to just use rsync that comes built-in with MacOS and in contrast to Finder can reliably resume an interrupted copy. You are suggesting to use a worse tool and then use another tool to verify that the worse tool did its job correctly...

 

[motulist]

That's way more effort than to just use rsync that comes built-in with MacOS and in contrast to Finder can reliably resume an interrupted copy. You are suggesting to use a worse tool and then use another tool to verify that the worse tool did its job correctly...

Not all people are comfortable with terminal commands. And if someone isn't already familiar with how a command line interface works then getting them able to simply execute the command would take more time and effort than using the other methods listed on this page. On top of which, if someone isn't already familiar with the rsync command in particular, then they would first have to do some relatively complicated research to determine if it does what they want so that they can be confident in the copy and not have to do a bit compare afterwards anyway.

Generally speaking, while one tool might be faster than another tool when initiation to completion time is measured on a stopwatch, that doesn't tell you if it will actually be faster for a real user to do the task. This is especially true when you're talking about a user who is familiar with one kind of tool but totally unfamiliar with the other kind.

But with that said... yes, rsync sounds like it might be a good way to do what OP wants to do. Good suggestion. If they're comfortable with the command line and confident in rsync's function then they should consider using it.

 

[okkibs]

I did list the command required to do a 1:1 copy, and about not being confident it copies correctly, the same would apply for any other tool. It's

rsync -a

where a stands for archive which just makes sure everything's copied 1:1. Then the source and last the destination. The -v switch can be added to provide a bit additional info. So

rsync -av /Volumes/source_disk/copy_this_directory /Volumes/destination_disk/paste_here

will take copy_this_directory and place that into paste_here.

And the convenient thing is that if you interrupt this (press CTRL+C to interrupt), you can run the same command again later and it will figure out where it stopped and automatically resume from there. Whereas with other tools you might be able to pause, but if you have to close the program, reboot MacOS or something, that might not be resumable. Finder can't do it, it has a resume feature since either Big Sur or Monterey, but it doesn't work properly across different disks.

 

[motulist]

I did list the command required to do a 1:1 copy, and about not being confident it copies correctly, the same would apply for any other tool. It's

rsync -a

where a stands for archive which just makes sure everything's copied 1:1. Then the source and last the destination. The -v switch can be added to provide a bit additional info. So

rsync -av /Volumes/source_disk/copy_this_directory /Volumes/destination_disk/paste_here

will take copy_this_directory and place that into paste_here.

And the convenient thing is that if you interrupt this (press CTRL+C to interrupt), you can run the same command again later and it will figure out where it stopped and automatically resume from there. Whereas with other tools you might be able to pause, but if you have to close the program, reboot MacOS or something, that might not be resumable. Finder can't do it, it has a resume feature since either Big Sur or Monterey, but it doesn't work properly across different disks.

Thanks for the detailed usage example! I'm not OP but I'll definitely try using this in the future.