MacBook/Lion sleeping during backups?

in Genius Bar edited January 2014
I upgraded my wife's MacBook to Lion the evening of the release. For the most part, everything has gone very smoothly. However, Time Machine backups (to a Time Capsule) are often extremely slow. They are also affecting the computer's performance (speed and heat) enough for my wife to complain.

I investigated a bit last night, and watched the computer work pretty hard for about 20 minutes on a 2MB backup. That's not right! Most of the time was spent preparing and cleaning up. A subsequent backup seemed normal.

I checked the logs (using the Time Machine Buddy widget), and found that several prior backups had failed when the drive disconnected. The long backup was locating and repairing corruption issues. Previous failed backups were in the process of attempting repairs when the failure occurred. The normal backup was, well, normal. We also have a Mini on Lion, which backs up to a USB-connected drive. Time Machine performs normally, and the logs don't show any errors.

When we first bought the MacBook and Time Capsule (about 3 years ago), we were having similar Time Machine problems. A common usage pattern was to open it, check something online quickly, and then re-close it (forcing sleep). We realized that it would often start a backup cycle when it woke; and learned to check and wait a minute or two for it to complete before closing. Problem resolved.

I suspect the MacBook is going to sleep in the middle of a backup cycle when otherwise idle, causing the in-progress backup to fail. The next backup takes longer due to the corruption caused, and is more likely to fail again.

I don't think this is related, but it could be: Last week, our WiFi stopped working in the middle of the day. When I got home from work, I found that the Time Capsule was not operating (light off, cold to the touch). I unplugged it and plugged it back in, and everything came back, drive diagnostics were OK. That has only happened the one time in three years, and I haven't seen any further evidence that the TC may be having problems.

Is there any way to confirm this is the cause? If so, is there any current solution to prevent the computer from sleeping during backups?


  • Reply 1 of 1
    smaxsmax Posts: 360member
    I noticed that my backups were taking forever to start and finish, at least at first. It was probably a result of my cat attacking the power cord to my backup drive... I really want to kill him sometimes.

    Anyway, I don't know of a way to prevent the computer from going to sleep based solely on TM (I would think that TM would prevent the computer from going to sleep anyway), but you could use Caffeine (the program, it's in the App Store for free) to make sure your computer stays awake until you know the backup has completed.
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