There are several possible reasons for wanting to boot from a USB drive, I suppose, but mine came from this thought experiment: I’ve been diligently making regular system backups of my Dell XPS 12 for a while and today I wondered if I would be able to recover from, say, a crashed hard drive or – a much better scenario – from upgrading the hard drive to a higher capacity one. In fact, this latter scenario is the one that interests me: I’m contemplating a 480GB drive (currently the Crucial M500 is $280 from newegg.com) to replace the 240GB drive that I bought a year ago for my Dell XPS 12.
The first big issue here I suppose is this: has my backup program really created a bootable partition on my external USB drive so that I can boot from it? After all, my backup would be pretty useless if I couldn’t boot to restore the system from it. Actually, that is the first law of backups: you haven’t really created a backup if you haven’t successfully restored from it. If you can’t, you’ve just been moving bits around and wasting electricity for the past N months and are – to put it ever so delicately – screwed.
The second issue is that the XPS 12 (like all machines that are built for Windows 8 or later) uses UEFI and Secure Boot for setup, not the traditional BIOS. How do you boot from a USB drive in this scenario?
For my backups of the XPS 12, I use Dell Backup and Recovery (DBAR), the Premium version. Usually, I’m an Acronis True Image man, but since the Basic version was pre-installed on the machine I decided to give it a go (the Premium version is a paid upgrade). As it happens, I’m happy with it: it does what I want it to do, which is make a complete system backup regularly – I’m not that interested in “data” or file backups, it’s the whole enchilada or nothing for me on the XPS 12. The first time you make a system backup with DBAR onto an external drive, it forces you to repartition and reformat the drive so that it can create a bootable partition, after which it backs up your system onto it. This I did, on a brand new WD My Passport drive that I’d bought for the occasion. So far, the weekly or so system backups I’ve been doing have proceeded without a hitch.
But… can I boot from it and hence recover from it? So, onto the next issue: just how do you boot from an external drive?
It turns out that, for the XPS 12 – despite the lack of hints – there are two keys you can press as it boots. F2 will navigate to the hardware setup page and F12 will navigate to the boot options page. By all means, explore the F2 setup and compare/contrast with ye olde BIOS setup, but F12 is the one you need. When I boot with the external drive plugged in and pressing F12, I get a screen which allows me to boot either the normal “Windows Boot Manager” or from “EFI USB1 PATH1” (or something similar – it depends on which USB port you are using). Select the second option and press Enter and the machine will boot from the external drive. Unlike other blogs out there suggesting you also need to disable Secure Boot to do this, I found that it is not necessary.
So, now to plonk down the $280 for a bigger mSata SSD…