Help. Time machine overwrote all the backups.

[globalhawk]

Hi, guys.

I got myself a serious problem here.
Last night I used time machine to backup the whole disk to a usb disk (backup file is about 300G). Then I did a clean installation of Lion. I connected the usb disk back to mac and went out. After I came back, what I can find from the usb disk is only a 'small' backup (90G). The old one is gone. All my data are gone now. Can anybody help? The disk is 500G so the old backup should not be deleted anyway.

 

[maflynn]

How much space did you have free on the disk?

TM will delete the prior back up when it requires the space even if its the only one. Personally I hold off using TM after an OS upgrade for this reason. I want to freeze my TM backup incase I want to go back.

In all likelihood if TM deleted the old one, its gone forever

 

[robgendreau]

Aaargh.

You have to understand that you deleted everything. That's what a clean install is, essentially blanking everything out. So in essence you had a new machine. So apparently time machine decided to back up your new, "clean" installation and figured you didn't want the other stuff. Next time do a regular install.

Get yourself some software that can attempt data recovery; meanwhile, don't use that external lest more stuff gets overwritten.