I recently gave Time Machine a new disc partition to play with. It has just finished its first backup which apparently used 404.97GB. This is odd since the Mac's hard drive only has 369.4GB on it in total - and Applications and System files are excluded from the backup.
Any ideas why Time Machine is being so profligate with my precious disc space?
Thanks Euan. I'm not sure what extra details you would have wished. One thing though, when the backup was in progress, it was reporting that it had done xGB out of yGB, together with an estimated time remaining. When I looked again (some four hours later), the progress bar showed it about 7/8 complete, x was still incrementing nicely - but y was also incrementing at the same rate! Not surprisingly, underneath it said 'Calculating time remaining'.
As a matter of interest, I still have on my desktop a screenshot of an event back in 2010 where the get info panel reports that my external hard drive has a capacity of 1TB of which 599.22GB are used, 400.85GB available. All well and good, but the finder window beside it shows Time Machine's Backups.backupdb folder as being 3.38TB in size! My guess then was that there is something about the way Time Machine works that screws up the finder's size calculations. Maybe the same thing was making a nonsense of the progress bar this time?
Anyway, the backup eventually concluded successfully so, as long as subsequent incremental backups proceed normally, I don't propose to investigate any further.
Trevor Hewson 