I have reinstalled my Mac OS (10.9) and had to specify again my external hard drive for backups in Time Machine preferences. Now i can enter Time Machine and see my previous backups.
However, Time Machine preferences show
Oldest backup: None
Latest backup: None
In particular, the estimated size for a new backup indicates that it will have to make a complete backup, without taking into account that most files in my home directory have not changed since the previous backup (before the Mac OS reinstallation).
Can i configure Time Machine to recognize the previous backups and to only backup modified files in my home directory?