Time machine simply stopped working

Question

I backed up my iMac weekly to a Lacie 500 GB HD, then went away for a few weeks so I disconnected (as I normally do when not in use). Now, when I want to back up it gets to 78 MB of 6 GB to back up then it stops. I tried with a different partition of the HD which doesn't work either.
Also, when I turned on the Lacie, I went into Time Machine but it's frozen, won't let me look at previous back ups, won't let me do anything apart from exit.
I'm puzzled as 2 weeks ago I would've said this is a rock solid and useful part of Leopard. Now?

Answer 1

Jon,
On every drive, there is first written a "partition map." It is this map that describes what volumes (partitions) exist on the drive, how large each one is, where they begin and end, etc. In a sense, it is like the "Table of Contents" in a book, and the partitions within it are like chapters. There are several schemes that are used to write this map, like different languages, or different dialects. PCs can access drives that use various schemes, but WIndows can only be installed on one that uses the "Master Boot Record" method of writing the map.
PPC Macs used the traditional Apple scheme, the "Apple Partition Map" scheme. Just like PCs, they can access drives that use other schemes, but the PPC version of OS X can only be installed on a drive that uses the "APM" scheme. The Intel version of OS X, on the other hand, requires a drive that uses the newer "GUID" scheme.
A side-effect of this is that Time Machine must have the a drive with the same scheme as the host, in order to correctly store the backup from that machine. For an Intel Mac, the external drive must use the "GUID" scheme. For a PPC Mac, the "APM" scheme. Does this clarify things?
I am trying to save all my data - 95 GB onto a partition that is more than twice that size and it saves about 20 MB before freezing yet again....
Are you saying that you have repartitioned your external drive, and yet your new attempts at running Time Machine are failing? If so, I am concerned. I mentioned a potential disk error earlier, but in the context of your external drive. When some form of copy action fails by "freezing," the most likely cause is a disk error, somewhere. In the case of copying from one drive to another, that disk error could be on the source, or on the destination. Since the fact that the external has just been formatted would tend to rule it out, I am concerned that you might have one on your Mac's internal drive.
If you are trying and failing to run Time Machine or make copies after having formatted that external, please use Disk Utility to check your internal drive for errors.
Something else, though: Are you absolutely certain that the Time Machine backup is "freezing?" In many cases, when making the initial backup, Time Machine can and does take a very long time to copy data during the first half of the backup process. It might copy 20 MBs, then "think" for 5 minutes, then copy 200 MBs, then think for 1, then copy a whole 6 GBs before stopping to think again. Are you certain that you have given it long enough?
Scott