Flash drive (aka usb pen drive) sucks. Even a 10 year old 10GB HDD outperforms a today's 8GB flash drive. What i meant by flash drive sucks is the write operation works very poorly in usb drive, which makes it bad candidate for any use other than backup and temporary usage. I tried to use a sparking new 16GB flash drive as a portable hard disk, by installing ubuntu 12.04 onto the flash drive, instead of my sata hdd. Installation took 12x time or so more time than it would have been with my sata hdd. And after installation using the flash drive slowed the os to a crawl. Never ever will i think of using a portable usb flash drive as a hdd or atleast till usb io performance is near current sata hdd speed. I would suggest anybody thinking of using pen drive for installing os, as better dont do, you will have a bad experiences.