Matt Connolly's Blog

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Monthly Archives: November 2009

Time Machine backup very slow – Finder interference

I recently bought a brand new 1TB FW drive, formatted it for Mac (Mac OS Extended Journaled), and set it up to do a fresh TM back, about 180GB.

After 18 hours, it had backed up only 60GB, averaging just under 1MB/sec. Abysmally slow for a brand new drive, which bench tests over 30MB/sec sustained reads and writes.

I was watching the Console logs for anything unusual, and also had the Activity Monitor open watching the Disk Activity. I noticed that the Finder was using a lot of CPU – don’t know why.

So, using Activity Monitor, I quit the Finder.

Suddenly the disk activity to the FW drive jumped from less than 2MB/s to over 30MB/s. The rest of the backup completed in under 2 hours.

It seems that whatever the Finder was doing was interfering massively with Time Machine’s performance.

Using Mac OS X 10.6.1 Snow Leopard and a 1TB Western Digital My Book Home drive.