apropriate HD space for Timemachine backup

[zoran]

What should the optimum space of my external HD be, in order to keep my Timemachine backup in? My MBPros HD is 185GB, how big should the external drive in which the TM backup will be made? And why?

 

[BobZune]

There is no specific optimum - bigger the better. The rule of thumb is for TM partition to be about twice the size of the partition(s) you want to backup. For your purpose, I'd suggest a 320GB or bigger size. [Backup does not equal archive, so your most precious data should be archived, preferably off site.]