Restoring from a Time Machine Backup Took Four Days!

6 11 2007

Recently, a data corruption event occurred on my Intel iMac. The computer would not boot. Luckily, it had Leopard installed, and it was being fully backed up with Time Machine. So, I decided to do a full restore of the entire disk using the Time MAchine backup.

The iMac has a 120GB hard disk containing about 100GB of data. Time Machine was backing up to an external 500GB hard disk over USB 2. To do a full restore of the computer from a Time Machine backup, you start up the computer using your OS X install disk. There is a menu item to restore from a Time Machine backup. Simply choose which backup you wish to use, and it begins, doing the rest automatically.

The progress bar started calculating the time remaining to complete the backup, and in a few moments it indicated… 170 hours to complete! Progress bar time estimates typically start conservatively, and tone down to be more accurate after a little while. It did, a little – to about 100 hours. This seemed startling – You can copy a 100GB disk using Disk Utility or SuperDuper in a tiny fraction of that time. But, having the time and curiosity, I let it run. It indeed took over 100 hours to complete the restore of 100GB of data.

Holy cow! Almost four days to restore a system from a Time Machine backup! The restore was successful, but if this hour-per-gigabyte rate is typical, it is something that needs improvement right away!

So, has anyone else had occasion to do a full restore of this kind? Did it take an incredibly long time, or was my experience an exception?




7 responses

9 11 2007

As an experiment, I tried the very same restore again. Same computer and disks, same Time Machine backup. This time it took only three hours, a more normal time. What caused the difference? I don’t know, because it was the very same restore, as far as I can tell.

18 11 2007

I wonder if the USB connection somehow got downgraded to USB 1.1 – I can imaging the restore taking that long over a slow USB 1 connection, with the zillion files to write. glad to hear it was reasonable later using the same exact machine and backup set.

16 12 2007

very interesting, but I don’t agree with you

18 12 2007

I had a similar problem. The restore software told me that it would take 17 hours to restore my disk (about 30 gigs) which made absolutely NO sense to me. After digging around, I discovered that the USB 2 connection defaults to USB 1.1 when the drive is connected to my Mac at start-up. If I waited to plug the drive in just prior to the restore process, it connected as USB 2 and was much faster – about one hour restore time.


1 03 2008
Jac Dubois

Consider yourself lucky, Tim. I had to restore up a single application. The file size was 105 MB and Time Machine estimated the time to restore would be 17 hour! My external drive is connected via eSATA and an ExpressCard 34. I let it run overnight. The following morning, it was only about halfway completed. I canceled the restore process and found a workaround. An Applecare rep I spoke with was no help at all. He told me that this sort of performance is not unusual with Time Machine. Glad I didn’t have to do a full restore. Anyone know of a better backup solution?

28 03 2008

I am now doing the system Restore over the air using the time capsule. I have around 130GB to restore. It took some time to let the TM RESTORE to calculate required disk space (about 30min) and then it estimated that it should take 14h which then increased to around 24. For now it is going a bit faster than the estimate says. I remember that it took around the same time to make the full backup (well, in the TM help it is said to leave the backup program over the night – quite honest, in my opinion), so I think it is quite ok and I decided to wait. I will see…

21 07 2008

Will everything be restored using the time capsule?
Applications and settings of everything at least?

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