MacOS – Copying files from a damaged Mac – Finder or CCC

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I have a Mac which can't boot up (it sees the prohibitory sign when it's turned on). I am going to do a clean reinstall of macOS on it. I want to keep the data somewhere, of course, so I don't lose all my files.

Since the Mac is damaged, do I need to make a clone of the drive (using Carbon Copy Cloner) or will a simply copy and paste of the drive to the target drive from the Finder do? I don't need the copied data to form a bootable drive, as it is damaged anyway. I just want to keep the personal files and folders intact, and perhaps the applications as well so I know what I had installed on the drive.

P.S. I'd rather not use CCC or any external programs if that's possible. I'm running macOS off a USB drive and it's incredibly slow, so third-party software is merely a hindrance.

Best Answer

If you have a functioning copy of macOS running from a USB you can still set up Time Machine to backup your internal drive to the target drive. This would be your best option to ensure you're capturing a full backup, alhough of course the first backup will take quite some time. However, just copying and pasting all your data would also take some time.

You could just do a copy and paste within Finder from your internal drive to target drive, but you do risk missing data that you may not want to lose. For example, if you use the default macOS Mail app, all the emails etc are stored in the User's library folder.

Related Solutions

MacOS – continue to use a Mac while Carbon Copy Cloner is cloning its HDD

The Carbon Copy Cloner FAQ states:

Yes and no, it really depends. Performance will be affected during the clone (especially the first one) as CCC reads the entire source volume and writes to the destination volume. If your work is "disk bound" -- that is your applications are reading or writing to either the source or destination, then you'll notice a performance hit. If you're just reading email or writing a Pages document, then you probably won't notice the performance hit.

Affecting the accuracy of the backup task is something else that should be considered. Typically it's OK to work from the source volume while you're copying it, with the understanding that if CCC copied a file, then you open it, make changes, save it, then CCC completes the backup task, the modified version of your document is not backed up (this time around). Typically that's no big deal, the modifications will get backed up the next time the backup task runs. More importantly, though, if you're working with large files (mounted disk image, Entourage email database, VMWare/Parallels container) during the backup operation, it is possible that those large files could be modified while CCC is backing up that file. This won't affect the source file, but there's a good chance that the backup version of that file will be corrupt. For this reason it is a good idea to stop using applications that may be modifying large files.

TL;DR: there is performance hit depending on the intensity of file I/O you produce; files you work on will not be backed up; large files may get corrupted.

The best way to clone a disk between two Macs

You can use the dd command to make a bit-perfect clone of a drive. It's a command line tool that ships with OS X. In order to make the clone perfect you'll need to ensure the source and the destination aren't actively in use.

To prepare for the clone I recommend creating a secondary boot disk that you can boot from. Your source for the clone should be an offline volume, not in use, when you're making the copy. Otherwise you risk copying things that are in incomplete states on disk.

With your machine booted to your secondary boot disk, log in and fire up a Terminal or iTerm window.

Run diskutil to get a list of your available drives. One of them will be your target drive you're trying to clone. The other will be your source drive. For example:

> diskutil list
/dev/disk0
   #:                       TYPE NAME                    SIZE       IDENTIFIER
   0:      GUID_partition_scheme                        *320.1 GB   disk0
   1:                        EFI                         209.7 MB   disk0s1
   2:                  Apple_HFS Macintosh HD            319.2 GB   disk0s2
   3:                 Apple_Boot Recovery HD             650.0 MB   disk0s3       
/dev/disk1
   #:                       TYPE NAME                    SIZE       IDENTIFIER
   0:      GUID_partition_scheme                        *500.1 GB   disk1
   1:                        EFI                         209.7 MB   disk1s1
   2:                  Apple_HFS Backup                  499.8 GB   disk1s2
/dev/disk2
   #:                       TYPE NAME                    SIZE       IDENTIFIER
   0:      GUID_partition_scheme                        *500.1 GB   disk2
   1:                        EFI                         209.7 MB   disk2s1
   2:                  Apple_HFS Clone                   499.8 GB   disk2s2

Let's say that Macintosh HD (disk0) is the source and Clone (disk2) is the target for our dd operation. Start the clone with:

> sudo dd if=/dev/rdisk0 of=/dev/rdisk2 bs=1m conv=noerror,sync

When dd finishes you may see an error like this:

dd: /dev/rdisk2: short write on character device
dd: /dev/rdisk2: Input/output error
3726+1 records in
3726+1 records out
500107862016 bytes transferred in 14584.393113 secs (34290619 bytes/sec)

That last error message is actually okay. The last block written was a short block because there wasn't a full 1MB block to copy. No worries.

Now you've got a bit-wise perfect clone of your Macintosh HD drive. Reboot your system using the Macintosh HD drive and enjoy your clone!

Best Answer

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MacOS – continue to use a Mac while Carbon Copy Cloner is cloning its HDD

The best way to clone a disk between two Macs

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