Yes you can do it excluding the initial boot. In the general view of the Raspberry PI architecture the Micro SD card as a matter of fact acts in the same way (and replacing it) of the flash memory in most of the Linux embedded devices. After the boot has started, you can make your Raspi to run Linux from any kind of external support, including a memory stick, a USB memory, a USB hard disk or ssd. I wrote a complete tutorial on this following step-by-step the procedure; you can find it here: Raspberry PI: USB hard disk boot
Yes you can do it excluding the initial boot. In the general view of the Raspberry PI architecture the Micro SD card as a matter of fact acts in the same way (and replacing it) of the flash memory in most of the Linux embedded devices. After the boot has started, you can make your Raspi to run Linux from any kind of external support, including a memory stick, a USB memory, a USB hard disk or ssd. I wrote a complete tutorial on this following step-by-step the procedure; you can find it here: Raspberry PI: USB hard disk boot
