Saving the contents of my Macbook pro HD

[jdubyat2]

if I copy my Macintosh HD and paste it to an external HD will all my files be saved an accessible if I reformat my computer?

 

[simsaladimbamba]

No, as the various permissions will not allow a simple copying via Finder of the entire Macintosh HD.
Use CarbonCopyCloner or SuperDuper to make a 1:1 copy to an external HDD.

How to format a new HDD to install Mac OS X onto (or make a bootable copy onto)​

 

[Yahooligan]

Or use Time Machine, which can be restored to a new/formatted drive relatively easily. The bonus with Time Machine is that as long as you keep the drive connected it will help make sure that you always have the most recent data backed up (It runs every hour). I don't use 3rd party apps for backups or copying drives as I've found the built-in OS X apps work just fine for these tasks.