how long should it take to copy a Time Machine drive to another drive?

Question

how long should it take to copy a Time Machine drive to another drive?

I have one year of Time Machine backups (500GB) on a drive that I think may be failing. Rather than lose them, I'm attempting to copy them to another external drive (both are USB 3) by following Apple directions in a tech note here. .It's now been 46 hour, and Finder is still calculating the number of files to be copied (currently at 2.6 million).

Is this normal?
I tried this once before under an earlier version of Mac OS X and—although many of the backups contained hard links to unchanged files (essentially Time Machine-created aliases)—on copying them, Finder tried to move multiple full copies of each file. As a result, the destination drive was completely filled before it finished copying only a handful of the many, many backups. Does this still happen, or has it been fixed in Catalina?

iMac 27" 5K, macOS 10.15

Posted on Jan 16, 2020 4:17 PM

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Answer 1

Best reply

John Galt

Level 10

141,296 points

Jan 16, 2020 4:51 PM in response to Steven Schwartz1

Yes, if you follow Apple's instructions.

They certainly work, but when transferring one Time Machine’s contents from one disk to another I find it much easier, faster, and more convenient to simply use Disk Utility’s Restore function: Restore a disk using Disk Utility on Mac - Apple Support.

It will probably finish in a few hours, while following Apple's instructions will certainly take several days.

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Answer 2

Jan 18, 2020 8:13 AM in response to Steven Schwartz1

Hi Steven,

Yes this is normal. Sometimes Finder will not be correct especially if you are copying a lot of files.
Yes this was fixed in Catalina. Depending on what you are on. The beta version of Catalina may have issues.

[Edited by Moderator]

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Answer 3

Jan 16, 2020 5:27 PM in response to John Galt

In the last hour, I finally remembered what I did to solve this problem a couple of years ago. I used SuperDuper!, a free utility that can easily perform this task. Within a minute, it determined that there were 13,000,000 files, so the Finder file counting process described above was only 1/6 of the way through! Within a couple of minutes, SuperDuper! was happily copying from one disk to the other.

After SuperDuper! finishes, I’ll set the target drive as the new Time Machine drive, check out some of the copies, and—if all is well—erase the original drive and send it back to the manufacturer. If there are issues, I’ll try Restore. Thanks for weighing in!

By the way, does Restore have the old issue of treating Time Machinr hard links as actual files, resulting in the target drive ending up much larger than the source drive; i.e., filling it? Or will the space used in the target be close to that of the source?

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Answer 4

John Galt

Level 10

141,296 points

Jan 16, 2020 5:28 PM in response to Steven Schwartz1

That's only the counting process, as you wrote. Copying doesn't even begin until after completing that task. It's absurd.

Extrapolation isn't very accurate but if you were to do that the entire process from start to finish would require about three weeks.

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Answer 5

Jan 16, 2020 5:42 PM in response to John Galt

And given that there’s no guarantee that it would work (or the source drive might fail during the process), both of the other options look mighty good!

It would be extremely helpful if Apple’s main post on this process would mention these two considerably speedier options.

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Answer 6

Jan 17, 2020 7:57 PM in response to John Galt

Update: As expected, SuperDuper! is doing its job. After 24 hours, it’s copied 4/5 of the files to the target drive (400 out of 500GB). However, it still has to wend its way thru an additional 5.5 million files to determine which ones need to be copied.

Did you find Restore to be a lot speedier for this task? (Keep in mind that my case involves a full year of backups.)

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Answer 7

Jan 18, 2020 12:35 PM in response to John Galt

SuperDuper! just finished. It took around 40 hours to complete the copy of about two years' of Time Machine backups to the target drive. So it was substantially faster for me than using Apple's Finder copy recommendation—given that I was already at 48 hours and it had only counted around 20% of the files that would need to be copied.

After I receive the replacement drive, I'll try Restore to see how long that takes to copy everything back.

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