I thought, I like to share this as Google didn't throw me anything useful when I was the victim of myself and my puppy didn't boot OSX anymore. "Life, loathe it or ignore it, you can't like it": Your MBA's OSX doesn't start anymore, you sitting in a hotel, and need to be up and running again next morning. You don't want to go back from Osaka to Tokyo by taxi at night to do it with your equipment at home. It gets worse: No second computer to use for remote disc, only one USB port, Superdrive doesn't work on a USB hub. Not just a towel with you: A full(!) and hopefully recent Time Machine backup on a USB storage, your Superdrive and MacOSX Install DVD (not needed if coming prepared, see tips at the end). Bar in the vicinity! == The Theory: EFI doesn't care much for boot flags when it comes to GUID partitioned drives. So, lets move the MacOSX Installer to the internal storage. QED: 1. Connect the Superdrive and boot from the MacOSX Install DVD 2. Choose Disk Utility form the Tools menu. 3. Create two partitions on your hard drive. P1, will be your partition to install onto. P2, will be used for the installer. Using P2 for the installer lets you remove it and resize P1 later on (Disk Utility does not let you resize partition towards the top!). If you like to keep the installer permanently on your drive, P1 can also be used for the purpose. For the installer's partition size use 7.3GB, when used as P1, or 7.8GB when used as P2. Disk Utility tends to use its own formula on partitions following P1 (i.e the required 7.3GB will become 6.85). Anyway, after trying a bit, these settings are just above the required size for my 10.5.5 installer DVD which came with my Rev B. You can verify the required size by clicking the DVD icon in Disk Utility. Look at the byte count, not GB! 4. I will use P2. 5. Click the P2 icon and choose the Restore tab. As source drag the installer's DVD icon into the prompt, as target, the P2 icon. Ready, set, go! 6. Go down to the bar for a Pan Galactic Gargle Blaster and a chat with the cute bar keeper who turns out to mix a wicked Vodka Martini instead. This will take about half an hour. Don't worry, you can come back for step 13. 7. Once finished, quit Disk Utility and power off. 8. Disconnect the Superdrive and connect your external storage with the Time Machine backup. 9. Start that puppy. It should boot now from the P2 and run the installer. 10. Choose Restore from Time Machine backup from the Tools menu, Continue.. 11. Possibly you see now your TM backup disk in the source list. If not, start Disk Utility and try to mount the USB disk manually, quit Disk Utility and back to the Restorer. 12. Choose your source and then your target, latter in my case is P1. 13. The Restorer will now check for the required size and start restoring. If you certain you have enough space, go back to the bar. 70GB backup took something less than 3 hours. 14. Being slightly drunk but still well dressed, you eventually will be received with the Restart prompt. Hit it and magically everything seems like it was the last time you backed up to TM. If you used P2, you can remove it now with Disk Utility and resize your OSX partition to the full size to make it reality. 15. Try to get some sleep. Things to tell myself: - prepare to repartition your TM disk and use one partition for an installer being with you all the time. - alternatively, use an 8GB+ USB stick as your MacOSX install disk and a USB hub can be used.