How does Time Machine handles old files

[fstigre]

Hi,

I have been using Time Machine for about a year now and it works great but I was wondering what TM does when my hard drive gets full. I believe it deletes old files, but what if those old files have been backed up only once, are they going to be deleted?

Other question, why is that my external HD, the one Im using for TM has three times more used space than what my local HD has? Does that means that TM has backed my stuff three time, I thought it only backs up the files that have been change?.

Thanks a lot for your help.

 

[waw74]

It backs up files that have changed, so if you change a file once a day, you will have 7 copies of that file from the last week in your backups. which is why it's so large.

as far as old files and making space, in the above example, to make space it would get rid of the oldest copy of that file first. so you could only go back to versions of the file from the last 6 days.

also depending on your settings, it will back up every hour, so you can go back to versions from earlier today. But will clean up multiple versions for days further in the past. so you might have 3 or 4 copies from today (1, 2, 3 hours ago), but only one version from a few days ago, so 4, 5, 6 days ago and not 4 days and 3 hours, 4 days and 4 hours etc.

it should always keep at least one copy of each file.

these are all just an explanation of the basics. actual results may very slightly

 

[fstigre]

Thanks a lot for the clarification.