Slow iPad backup issue

The problem

The “backup iPad” function in iTunes backs up only one or two files per second. This is no problem for large files (which may take longer), but particularly applies to very small files. Some applications have hundreds or even thousands of such small files. One application consisted of 80 MBytes made up of 6000 small files. It thus took 1-2 hours to backup those 6000 files – despite the fact that only 80 MByte were being backed up.

Furthermore, the backup progress bar may seem to freeze during specific parts of the backup process (when large series of small files are being processed). Apparently the progress bar show what percentage of the data that needs to be backed up has been processed. This is normally acceptable, but in this extreme case the user is likely to conclude that the process has crashed. In my case, backing up only 80 MBytes (out of a total backup of 1.5 Gbytes) took the majority of the time.

Symptoms

Before updating the iPad’s firmware using iTunes, Apple backups any user data on the device.

The main symptom is that this backup process takes very long: hours. And that it takes much longer than it originally took when the iPad was brand new. And much longer than one would expect for the amount of data being moved across the USB cable to the PC or Mac and to a local or network drive. Suggestions in forums to use better USB cables are incidentally unlikely to help.

On a PC you can watch this backup data accumulate in a directory (used by iTunes) named, for example,

C:\Users\Peter\AppData\Roaming\Apple Computer\MobileSync\Backup\a40DigitHexNumberProbablyIdentifyingyourDevice

There are utilities available by m4ko.de that automate the analysis of what files are being backed up (but you need to find the iTunes backup directory manually anyway).

The above has been observed back in April 2010 (and the issue is still not resolved in iOS 3.2). They also concluded that many applications generated hundreds or thousands of files, and that this essentially makes it look like the iPad backup process hangs. In my case one application (Granimator) consisted of least 6000 files with graphical elements. I can tell because the .mdinfo files contain the orignal file names like “Documents/packs/GP_moving_brands/shapes/white/4/shape_0445.png” which happens to belong to one of the Granimator shape packs. And the m4ko utilities can tell because they look at a domain name inside the .mdinfo files. Granimator is incidentally creating its own workaround for this problem – but this doesn’t help other applications.

Technical analysis

The cause seems to be:

  • every file that needs backing on the iPad up results in two files on the PC: the backup file named [hashnumber].mddata and a file with metadata named [hashnumber].mdinfo
  • there are a few log and manifest files that list the hash values of all backuped files – but these are not relevant here
  • somehow, only a few files per second can be backuped in this way – even if the files are only 1 kByte each
  • particularly the application AppleMobileDeviceService.exe and AppleMobileService.exe respectively read 1 MB/s and write 0.5 MByte per second to the local device (127.0.0.1) according to the Resource Monitor. Note that 127.0.0.1 may have a strange web address depending on the content of your hosts file, but this is just a distraction. This detour of the writing of the data via the TCP/IP network stack within the PC may explain some of the performance overhead.

Way forward?

Various Apps have been discovered that exhibit this problem – so the issue is clearly a design problem that makes the iPad (and iPhone and iPod Touch?) pretty much incompatible with applications that install hundreds or thousands of tiny files. Apple can solve this by either changing their backup method, or by adding an extra rule that developers need to adhere to get their App accepted for distribution via the App Store.

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19 Responses to Slow iPad backup issue

  1. Barry says:

    An excellent summary. Spending £700 on an iPad and waiting 15 hours for it to back up 30GB is totally unacceptable. Apple have been ignoring this issue for a long time. The more publicity it gets the better.

    • bob says:

      It is now March 2011 and the problem still exists!

      I found out yesterday and though I have only about 6 Gb on my iPad 3G 64, it is impossible to backup anything and as a result it is impossible to update the basic iPad software to v4…

      Apple stinks, I knew it all along, but my kids wanted me to buy an iPad.

      Yesterday I was on the edge of smashing the iPad with a hammer into the garbage can, after it turned out impossible to install Garbage Band….
      Even my whole windows Vista computer froze because of iTunes. Incredible that they need 90Mb for such a simple, basic program like iTunes……

      And that it doesn’t work.

      [minor typo’s removed by PvdH]

      • pvdhamer says:

        I am not a specialist in Apple stuff. But as far as I know:
        1) you should be able to backup your iPad. This “bug” only makes it take verrrrrry long. Use the utilities mentioned in my posting to watch progress. Then you can see what is taking a long time and decide whether you need to back that up.
        2) I get the impression that the slow-backup problem is gone on recent versions of iOS. So there may be hope.
        3) you can manually try to figure out what you need to save via Sync/backup. It can be faster to redownload stuff (e.g. Xinio magazines) than to back them up.
        4) If all else fails, iTunes allows you to do a “Restore” and then build up the content of the iPad from scratch. It installs the latest version of iOS. I did that yesterday because my upgrade to 4.2.1. didn’t go well. If you don’t have a backup, you may end loosing stuff (e.g. photos, music, whatever) that you don’t have on iTunes on the PC or on the PC itself.

        I agree that iTunes is poor quality software: it is indeed sometimes hard to use, and it indeed crashes (on the PC, but Apple may blame the PC for that?). But it is one of the top 100 software programs in the world. You have to use it occasionally (which is IMO weird: can’t I own an iPad without owning a PC or Mac?). Garbage Band -> Garage Band, but maybe you meant it as a joke.

    • Bert says:

      This problem still exist now 2012 with ipad3. What is going on? Why can’t they fix this?

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  3. R. Gilles says:

    coming home from holiday with > 3000 pictures and movie clips + apps and pdfs on my brand new ipad, never backed up. Asks for upgrade and starts saving the ipad… it’s been going for hours and the bar seems to be at 1/10th of full. I’m glad i’ve found this blog to calm down a bit but who knows how long the iPad battery will last because it doesn’t seem to recharge on the PC. Thanks Apple. How come they cannot just backup at USB speed. If they need some extra security, they should use PC or iPad power to do the trick, not play with users’ nerves.

    • pvdhamer says:

      R. Giles: You may be able to selectively backup. Your first priority is your own photos and movies. They should actually backup at USB 2 speed (say 100-200 Mbit/s = 10-20 MBytes/s = roughly 50 GBytes/hour). What I believe invariably causes slow backups is numerous small files that came with your Apps or their data (notably magazines). But although these small files may be worth backing up, they are less important than your own media files which are invariably larger and backup efficiently.

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  8. tegieng says:

    I just upgraded my ipad to 4.2.1 and used redsn0w to tethered jailbreak. I got good news, my backup used to take 24+ hours to finish now only took about 3 mins. I checked the backup files and Apple now used the iphone type to do the backup, not the other mdinfo type. So Apple did realize they did something wrong and corrected it.

  9. Michael says:

    I was having slow & stalled backup problems, but they went away when I plugged the iPad into a different USB port on my macbook. No change in the number or size of files but backup went really quickly after this ‘tweak’. So it may be an issue with the USB rather than with the content or backup software. And perhaps Apple has fixed this in the last 9 months anyway…

  10. Jacob says:

    Running 4.3.5 and I have been trying to backup for a few hours now even tried different usb ports – but no dice on my end… and now I can’t even cancel the backup! I am not sure why they would even do individual file backups in the first place, would make much more sense to compress all the files zip/gzip/tar etc… then do a transfer of the single file. I am in no way an expert in the @pple universe so what do I know? 🙂

  11. Dwight says:

    I am trying to upgrade my7 IPAD from IOS 4.3.4 to IOS 4.3.5 and am using a PC running Windows Vista Home Premium service pack 2.

    The backup has been running 6 hours now and I am leaving it to run overnight.

  12. richard jell says:

    I have had the same problem, left it on all night and it was still backing up. So i uninstalled itunes, disconnected the ipad and re installed itunes. My ipad now backed up in 30 seconds, just upgrading now to ios 5.
    My pc is running windows 7 64, I also disable any protection whilst doing this. By the way whilst I have wrote this the whole process is over!

  13. Tom says:

    Good grief. Backing up an iPad — started 13 HOURS ago and it’s still not done. There isn’t even that much on it. This is ridiculous. This is an iOS 3.2 device, I sure hope upgrading it to OS 5 improves this performance.

    • Tom says:

      So my MacBook spent 14+ hours backing up the iPad, then I started the iOS 5 install… AND IT STARTED ANOTHER BACKUP! WTF?! Over 3 hours on this one so far and only about 40% complete. I don’t dare try to stop it; I assume if I try to install the new OS again, it’ll just restart the backup process. Apple’s software quality superiority is a MYTH.

  14. Imelda says:

    iOS 5 also sucks,
    before I updated it I used of 4.3.5, when I did backup or sync my iPad all going smoothly. But after I use iOS 5, I can’t backup my iPad and iPhone. I turned off the automatic backup and only sync my iPad. For the first and second time sync were running well. But, now sync is taking too much time.

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