I keep seeing Time Machine doing a full backup of my ~80 GB hard disk. I see this a few times a week, when I first turn on my mac. During the day, I see Time Machine doing small incremental backups of ~100 MB, hourly.
Why does Time Machine does these big backups?
I also see the large backups in the logs here.
nanceki@Stephen-Nancekivells-iMac /v/log> bzcat system.log.* | grep backupd | grep Copied | grep GB| sort | less
Jul 23 08:46:32 Stephen-Nancekivells-iMac com.apple.backupd[7569]: Copied 0 bytes of 78.3 GB, 0 of 23051 items
Jul 23 08:47:31 Stephen-Nancekivells-iMac com.apple.backupd[7569]: Copied 5324 files (1.1 GB) from volume Macintosh HD.
Jul 24 08:55:37 Stephen-Nancekivells-iMac com.apple.backupd[20310]: Copied 0 bytes of 78.4 GB, 0 of 23013 items
Jul 24 09:52:18 Stephen-Nancekivells-iMac com.apple.backupd[20310]: Copied 24172 files (78.4 GB) from volume Macintosh HD.
Jul 28 13:43:25 Stephen-Nancekivells-iMac com.apple.backupd[98930]: Copied 0 bytes of 76.5 GB, 0 of 4557 items
Jul 28 15:43:43 Stephen-Nancekivells-iMac com.apple.backupd[98930]: Copied 20.4 MB of 76.5 GB, 2477 of 4557 items
Jul 28 17:43:59 Stephen-Nancekivells-iMac com.apple.backupd[98930]: Copied 305.8 MB of 76.5 GB, 5797 of 5797 items
Jul 28 19:45:03 Stephen-Nancekivells-iMac com.apple.backupd[98930]: Copied 1015.8 MB of 76.5 GB, 5797 of 5797 items
Jul 28 21:44:58 Stephen-Nancekivells-iMac com.apple.backupd[98930]: Copied 1017.8 MB of 76.5 GB, 5797 of 5797 items
Jul 28 23:45:22 Stephen-Nancekivells-iMac com.apple.backupd[98930]: Copied 1.4 GB of 76.5 GB, 5797 of 5797 items
Jul 29 01:45:40 Stephen-Nancekivells-iMac com.apple.backupd[98930]: Copied 1.8 GB of 76.5 GB, 5797 of 5797 items
Jul 29 03:46:08 Stephen-Nancekivells-iMac com.apple.backupd[98930]: Copied 2.4 GB of 76.5 GB, 5797 of 5797 items
Jul 29 05:46:26 Stephen-Nancekivells-iMac com.apple.backupd[98930]: Copied 2.8 GB of 76.5 GB, 5797 of 5797 items
Jul 29 07:46:47 Stephen-Nancekivells-iMac com.apple.backupd[98930]: Copied 3.4 GB of 76.5 GB, 5797 of 5797 items
Jul 30 03:50:41 Stephen-Nancekivells-iMac com.apple.backupd[98930]: Copied 4.1 GB of 76.5 GB, 5800 of 5800 items
Jul 30 05:51:07 Stephen-Nancekivells-iMac com.apple.backupd[98930]: Copied 4.4 GB of 76.5 GB, 5800 of 5800 items
Jul 30 07:51:20 Stephen-Nancekivells-iMac com.apple.backupd[98930]: Copied 4.8 GB of 76.5 GB, 5800 of 5800 items
Jul 30 09:02:00 Stephen-Nancekivells-iMac com.apple.backupd[98930]: Copied 5.4 GB of 76.5 GB, 5800 of 5800 items
Jul 30 09:55:30 Stephen-Nancekivells-iMac com.apple.backupd[98930]: Copied 6598 files (76.5 GB) from volume Macintosh HD.
Jul 31 09:09:22 Stephen-Nancekivells-iMac com.apple.backupd[4793]: Copied 0 bytes of 76.5 GB, 0 of 4510 items
Jul 31 10:03:35 Stephen-Nancekivells-iMac com.apple.backupd[4793]: Copied 5615 files (76.5 GB) from volume Macintosh HD.
Best Answer
You could try using BackupLoupe to inspect exactly what has been copied in each backup. I find I have to exclude things like my web browser cache to keep the size of the backups down.