Zefan said:
Few seconds maybe for a quick format. For a normal non-quick it is a lot slower (Not sure why). Normally takes minutes for my rubbish WD120.
Qucik format just re-sets the file allocation tables and such to empty, so the disc will start afresh and overwrite whatever was there before, but the old data is still there.
A full (or low level) format actually re-writes all the sectors and tracks with clean data. That's why it take ages. I set up a Raid with 2 120's last weekend, took about two hours to format in windows!
I have heard that some companies can recover data from discs that have been 'low-level' formatted. I'm not sure how this is possible, might be that even a low level format leaves some residual magnetic signatures behind.