Mac OS X Time Machine advice

Apple’s Time Machine has saved my bacon a couple of times.  It’s not the only backup strategy I use (I’m trying to store more in the cloud), but it’s a darned useful one.

When switching to my new MacBook Pro, syncing up with my ten months of old Time Machine backups got hopelessly confused.  And I had wanted to repartition that external disk anyhow.  So… reformat, and restart Time Machine aimed at an empty disk.

Took forever.

The first 30 gigabytes took over 48 hours to transfer… at the princely data rate of 1.4 megabytes/sec.    And this is over a FireWire 800 cable!  I think a decent DSP can do that rate over a barbed wire fence.

I finally figured out that, even with 4 gigs of RAM, the system was overloaded with other processes (apparently Safari, Java, SpanningSync, and TweetDeck were particularly greedy) and was swapping virtual memory in and out like crazy.  I rebooted, logged in, held down the Shift key to disable startup processes, and left it alone.  The trick is letting Time Machine do its thing unimpeded.

The remaining 170 gigabytes transferred in 2 hours… a much more reasonable 188 megabits per second.  From Activity Monitor, three processes — Finder, backupd, and mds — took up essentially all of the CPU time, so refraining from running other programs probably helped.  Page outs and swaps never budged from zero.

If you’re frustrated by an agonizingly slow Time Machine initial backup, try it this way.  When you’re done, reboot normally, and subsequent incremental backups are speedy indeed. Hope this is useful to somebody…