Instead of asking the same questions asked many times before, and looking at FAQs, I'm going to post a question on a different take of the OS X installation. First, I'm running Lion on my 2012 MacBook Air. So far, no problems, and I'm actually happy with it, except for the fact that if I lose the drive, I also lose the data I have along with it. That's okay, because that is what backups are for. But when it comes to reinstalling, or even updating the OS, it still would go back on to the same piece of hardware (meaning, the internal drive). Or does it have to be that way? I ask that, because in my professional life as a Linux sysadmin, I'm running a boatload of virtual servers off of Dell servers, which the base OS is VMWare ESXi, which has the option of having the base OS installed onto a USB stick, leaving the internal drives solely for hosting the virtual servers or a datastore. That same process could be used on a Mac, could it not? But instead of a USB stick, use a SDHC card? I know that at that time, the 11" MBA came in a 64GB variant, meaning that the complete OS, after being installed, was definitely less than 64GB. So my questions are: How much space is taken up after a vanilla install of Mavericks? Nothing else but the base OS? If small enough, could it fit on something like a 64GB SDHC card? If so, how does read/write speeds compare between an SDHC card vs. various SSDs that Macs use? Finally, If the OS is installed on an SDHC card, if the internal drive isn't erased, that should give one the option of dual booting, should it not? If so, this would not only give me a 64GB to the 256GB internal drive I have by separating the OS off of the internal drive, plus also give me the ability to try out Mavericks without doing a full blown upgrade with no downgrade path. Comments? BL.