"Preparing to copy" for three full days — when to give up?

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Level 1

71 points

"Preparing to copy" for three full days — when to give up?

I am trying to move my data from a 4TB Time Machine disk to a new 6TB disk, because I have about a decade of files backed up and the 4TB disk is almost full. (Getting constant messages about TM deleting old backups.)

It is now Friday morning and I started the process on Tuesday afternoon, following the instructions at Time Machine: How to transfer backups from a current backup drive to a new backup drive - Apple Support— formatting the target disk properly and using the finder to copy the TM folder. So it's been about 60 hours, but the Finder still shows "Preparing to copy to <diskname>" and "Preparing to copy <at the moment, 19 million!> items". The number of files continues to increment, but preposterously slowly, updating every 5 minutes or so.

If the message is accurate, this means that the Finder is still figuring out where each file should go (the target disk is brand new, and empty)

At what point should I decide that something has gone wrong, give up, and start again? I am also living in fear that the system freezes, or I have a power failure, and I have to start the whole thing from scratch again. Thanks for any advice.

(Please don't tell me to just start a fresh TM disk rather than copying the old one, though of course that would save time and make my question irrelevant. That's not what I want to do here. Thanks.)

MacBook Pro, macOS Sierra (10.12.4), null

Posted on Apr 21, 2017 6:29 AM

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Answer 1

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dpdpdp Author

Level 1

71 points

May 6, 2017 8:25 AM in response to dpdpdp

Replying to my own post with a report on what worked and what did not work.

1. I kept the Apple-recommended copy operation going, and did not interrupt it. The entire process took 8 days (for 3.8 TB)!! At the end of this, I had a disk that Time Machine recognized, but it turned out that about 50% of the data had not been copied at all. There had been no error message or other notification.

2. Next, following a recommendation here, I tried SuperDuper. SuperDuper worked on the copy operation for about three days, and then timed out with an out of memory error. (This is on an iMac with 32GB memory.) The developer replied speedily, but indicated that there was nothing he could do.

3. Finally, following other recommendations on the web (and "dialabrain" just made the same recommendation above), I tried the Restore function in the Disk Utility app that comes with Sierra. To my amazement, that worked, and took only about 18 hours.

So the moral of the story (after two weeks of trying to solve this problem) is: yes, use "Restore" in Disk Utility.

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Answer 2

dpdpdp Author

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71 points

Apr 21, 2017 11:05 AM in response to dialabrain

Thanks, but I am not trying to do a Time Machine backup, but to copy my Time Machine data to a new hard drive. Probably the issues are similar, but not the same.

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Answer 3

dialabrain

Level 10

134,549 points

May 6, 2017 8:24 AM in response to dpdpdp

You're welcome.

Sorry I wasn't paying enough attention. You should be able to use Disk Utility's Restore function by selecting the old drive as the source and the new drive as the destination. Essentially "cloning" the old drive to the new drive. I've never tried moving 4TBs from one drive to another but I assume it could take awhile.

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Answer 4

ishrugged

Level 3

557 points

Apr 21, 2017 1:48 PM in response to dpdpdp

I've never done it. For your use-case, Mr. Pond's site has the same instructions as the Apple link with this bit of info at the beginning of his article:

If you find you need more space for Time Machine backups, or want to change locations (local to network, or vice-versa), your best bet is to simply start a new set of backups in the new location. Keep the old ones "on the shelf" until you're sure you don't need them. (If you're backing-up to a locally-connected disk, it's best to give it a different name.)

That's especially true for a large set of backups and/or more than a few month's worth; the larger the backups, the longer it takes to populate the "Star Wars" display, especially over a network; the monthly Verify Backups will take longer; and of course the possibility of corruption increases.

You can always browse and restore from the old backups, via the Browse Other Time Machine Disks option (hold down the Alt/Option key while selecting the Time Machine icon in your menubar, or control-click (right-click) the Time Machine icon in your Dock). See Question #17for details.

But if you want, in many cases you can copy your Time Machine backups to a new location. It will take a very long time (even a small set of backups will contain at least several hundred thousand files), and sometimes it's not easy. And there are some restrictions:

[...]

http://pondini.org/TM/18.html

From OS X Daily:

[...]

Open another Finder window with the new hard drive visible, then drag and drop the “Backups.backupdb” folder from the old drive to this new hard drive – this copy process may take a long time depending on the size of the backups and the speed of the drive interfaces, don’t be surprised if it takes several hours

[...]

http://osxdaily.com/2013/07/07/move-time-machine-backup-new-drive/

Yours is incrementing. I'd assume it's working at its necessary pace and wait....How long?

A way to monitor the I/O statistics is by using the iostat command in Terminal. You can learn about it by entering this command (starts at m, ends at the second t):

man iostat

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