TimeMachine backup problems

Launch the Console application by entering the first few letters of its name into a Spotlight search. Select "system.log" from the file list. Enter "backupd" (without the quotes) in the Filter text field. Post the messages from the last backup, beginning with "Starting standard backup." Post the log text, please, not a screenshot. Edit out excessive repeats, if any. Some personal information, such as the names of your files, may be included -- edit that out, too, but don’t remove the context.

Where do I enter "backupd"?

There isn't enough space on your backup volume for the data you're trying to back up. You don't have any past snapshots at all, and you can't create a new one.

I suggest you start a new backup set on another external hard drive at least 3x the capacity of the partition you're using now. You need more than one backup anyway -- one is not enough. Don't use that drive for anything else. Then repartition the first drive to allow at least three times as much space for TM. If that doesn't leave enough space for your mirror backup, put it on another drive, or just eliminate it. A mirror backup isn't really a necessity, just a convenience. Time Machine volumes are bootable if you back up your system files. If you don't do that, use Lion Recovery Disk Assistant to create a bootable recovery system on a USB flash drive.

OS X Lion: About Lion Recovery Disk Assistant

To add to Linc's advice, try to keep Time Machine at default settings. That is how it works best. People who complain about Time Machine almost always have some kind of funky exclusion strategy. People who just turn Time Machine on and let it run don't complain about it as much.

So does this mean that even 5x the amount of required space is insuffient?

No, because only files that have changed since the last backup are backed up. But I can't tell you how much backup space you need. It depends on your usage pattern. Three times the total current amount of data is just a rough estimate. If you have a lot of large files that change often, you may need much more.

Launch the Terminal application in any of the following ways:

☞ Enter the first few letters of its name into a Spotlight search. Select it in the results (it should be at the top.)

☞ In the Finder, select Go ▹ Utilities from the menu bar, or press the key combination shift-command-U. The application is in the folder that opens.

☞ Open LaunchPad. Click Utilities, then Terminal in the page that opens.

Drag or copy — do not type — the following line into the Terminal window, then press return:

sudo tmutil compare

You'll be prompted for your login password, which won't be displayed when you type it. You may get a one-time warning not to screw up.

The command will take at least a few minutes to run. Eventually some lines of output will appear below what you entered.

Each line that begins with a plus sign (“+”) represents a file that has been added to the source volume since the last snapshot was taken. These files have not been backed up yet.

Each line that begins with an exclamation point (“!”) represents a file that has changed on the source volume. These files have been backed up, but not in their present state.

Each line that begins with a minus sign (“-“) represents a file that has been removed from the source volume.

Files that you’ve excluded from backup, or that are excluded automatically, are ignored.

At the end of the output, you’ll get some lines like the following:

-------------------------------------

Added:

Removed:

Changed:

These lines show the total amount of data added, removed, or changed on the source(s) since the last snapshot.

The backup volume wasn't mounted. Mount it and try again.

I'm looking back at your console output in post 5 (before you changed partition sizes) and these two lines bother me:

Feb 13 22:01:43 new-iMac com.apple.backupd[2072]: System files exclusion changed.

Feb 13 22:01:44 new-iMac com.apple.backupd[2072]: Event store UUIDs don't match for volume: Lacie 1.15 TB general backup

at that time you were backing up to the 250 Gb partition, but backupd was complaining about the 1.1 Tb partition. and in fact, the complaint is that file UUIDs don't match (which would, of course, be why it wasn't deleting old backups - it chooses files to delete based on UUIDs).

I suspect you have some sort of odd interaction with CCC happening. Are you accidentally making your time machine backups from the clone drive? I'm asking that because that's the easiest way I can think of to get a file UUID to change; the system may not recognize the cloned drive as a clone and might assign new UUIDs to the files there.

You seem to have removed 479 GB of data since the last snapshot was taken. That could be because you've been backing up another volume that wasn't mounted at the time you ran the command.

In any case, the usefulness of the tmutil output is that it shows you which files are being copied and how much space they take up on the destination. A common reason for problems like yours is that a very large file, such as a virtual disk file for something like VMWare or Parallels, is being backed up. Since the file changes all the time, it has to be copied to each snapshot, quickly filling up the destination. The solution in such cases is to exclude that file from TM backup and back it, or its contents, up some other way, such as within Windows.