Yesterday, I installed an external hard disk for my Time Machine — well, a 1.6Tb partition of a 2Tb hard disk. I am running a new iMac with 512Gb SSD. The internal drive is about half full.
After a day, I have about 5 backups, and I find that I only have 448Gb available.
I am still trying to get the other folder sizes (understandably, this is taking a long time), but the first backup folder is about 250Gb. At a rough estimate, this suggests that the subsequent backups are about the same size. At this rate, I will run out by tomorrow.
I understood that the Time Machine backups are sort of differential, and that subsequent backups are mostly links to the original backup files.
The question is: is the size, being mis-reported, or is that a correct estimate of the space used?