Time Machine takes 8 Hours to back up 140 MB

Discussion in 'macOS' started by ayeying, Aug 29, 2008.

  1. ayeying macrumors 601


    Dec 5, 2007
    Yay Area, CA
    For some reason, this has happened twice now, I use a 500GB external USB2 hard drive for time machine back up, and both times, the time machine backs up SOOOO slow for no apparent reason.

    If I were to format the drive and redo the backup, the speed would resume to normal. Work for about 10-20 back ups then this problem occurs again. Time machine doesn't not show any errors, it just is slow. It takes about 2 hours for "Preparing Backup" then another 6 to backup 140 MB worth of files.

    At first I thought the drive might be bad but transferring a file via finder disproved that theory. Disk utility check was good also except the check was extremely long compared to before.

    There's no errors in console either.. its just slow.
  2. r0k macrumors 68040


    Mar 3, 2008
    There's only one way to say this...

    Time Machine is a work in progress.

    I called AppleCare because my Macbook at 6 kernel panics in rapid succession. I expected a hardware problem would be required to cause such a catastrophe. I made it all the way to level 3 support before I found out the truth. These kernel panics were caused by a "corrupt sparsebundle" file on my Time Capsule. The stimulus that brought this issue into my life was that I changed my Macbook from never sleeping to allow it to sleep after 4 hours. Then I got on a plane and went out of town for 2 weeks. I got home and let software update run and kaboom. Kernel Panic. I noticed that on the screen, the Time Machine arrow just started to move before the panic. I mentioned this to Apple support and they suggested I shut off Time Machine. Sure. No problem. Now I was back to a stable and useful machine with no backups. It turns out that when Time Machine is backing up wirelesssly and the Machine goes to sleep, file corruption occurs on the other end. I assumed this was related only to wireless backups so I've been sitting on wired gigabit ethernet ever since. Sleep is still disabled on my machine.

    Perhaps in your case, a similar issue is occurring. The issue could be caused by poor or intermittent connection (wifi, wired, usb, firewire, whatever) to the target volume or by the system unexpectedly going to sleep during a backup. And with backups hourly, chances are whenever the system tries to sleep there's a backup in progress. Except in your case instead of a kernel panic :eek: you get slow performance. Better than a kernel panic, but not exactly what you paid for. Here is a procedure to investigate this phenomenon, taken from what AppleCare had me try...

    1. Browse to the sparsebundle for your Time Machine backup and drag it to Disk Utility. Not the entire usb drive, just the sparsebundle containing your backup (which it turns out is really a disk image). Have Disk Utility repair it. If it repairs it successfully, your slow performance should be over.

    2. If the repair is not successful, ie it hangs or never completes in a reasonable time, delete your sparsebundle. It's too corrupt to be backed up to and chances are you couldn't restore from it if you wanted to. What? Am I really saying this? Yes. I'm quoting AppleCare here. If the target sparsebundle is too corrupt to back up to, chances are it's too corrupt to restore from. This is a big deal. A really big deal. In Time Machine we have ourselves a safety net with a huge gaping hole ripped in it. Let's hope this hole gets sewn shut very very soon.

    3. Complain to AppleCare about this. This is something we absolutely cannot live with. Time Machine should always work, never corrupt it's own backups and it should communicate with the OS to suspend gracefully if the system is going to sleep rather than get the rug pulled out mid-write and corrupt the target backup disk image. Time Machine should never "slow down" without explanation and instead should automatically run disk utility to repair the damage in the target volume as well as let the user know there was a problem with the backup. I never want to find out that a backup isn't good by trying to restore after a crash only to find the data isn't really safe.

Share This Page