I write my blogs using an early 2011 13” Macbook Air with MacOS 10.7.5. This is backed up over my network using Time Machine, which used to work pretty well, backing stuff reasonably quickly1. However, over the past few months it’s become slower and slower and I realized that I had to do something about this when it took 9 hours to back up 104MB of 6.5GB, which is frankly RUBBISH.
After digging around, I found a few rumours that Time Machine and Spotlight interact in some way, with Time Machine coming off worse.
The 'fix'2 for this problem is to simply disable Spotlight whilst backing up. You can do this by entering the following command in a terminal:
sudo launchctl unload -w /System/Library/LaunchDaemons/com.apple.metadata.mds.plist
This unloads the Spotlight mds from launchd. Having made this change my 6.5GB was backed up in a matter of minutes - a startling improvement.
Once your backup is complete, you can turn Spotlight on again with the following command:
sudo launchctl load -w /System/Library/LaunchDaemons/com.apple.metadata.mds.plist
I’m assuming that you don’t schedule Time Machine to perform hourly backups, if you do then you might want to leave Spotlight turned off; I have, as I hardly use it.
1One of the reasons I swapped to a Mac was that Windows backup had really poor performance no matter what I did.
2More of a work around - Apple needs to sort it out, it should just work.