10.6: Avoid slow and CPU-intensive Time Machine backups
Feb 03, '10 07:30:00AM • Contributed by: wayfarer
Feb 03, '10 07:30:00AM • Contributed by: wayfarer
On my Mac, Time Machine backups sometimes slow to a crawl, and stay like that for hours on end. After some digging, I discovered that Finder is often the culprit, and quitting Finder seems not to have any adverse impact on the backup -- but it does speed it up by an order of magnitude. Here's what happened in my case...
I had been making an initial Time Machine backup over a network. Initial write speeds were over 5mbps, but an hour later, it was down to 100kbps -- and CPU usage went up to almost 90%. I left it this way for four hours and there was no improvement -- at this rate, the backup would take a week.
A look at Activity Monitor showed almost all the CPU usage due to Finder, and a look at the 'Open Files and Ports' by Finder showed it accessing the Applications folder in the backup, crawling through all the application packages over and over again.
Fed up, I quit Finder and suddenly backup speed went back over 5mbps -- and the backup finished absolutely fine.
I don't know what Finder was doing, but it doesn't seem like anything crucial (I didn't notice anything in the logs). This was only seen on Snow Leopard, and over a network (although this happened to me with a FireWire backup device as well.).
[robg adds: I haven't seen this on my Macs, but if you're having Time Machine backup issues, it might be worth a look.]
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