Mac computers since OS X Lion came preinstalled with recovery partition. This partition allows us to recover our computer in case a serious problem occurs. Or, it can simply be useful when we want to repair our main internal HDD. Your Mac machine comes preinstalled with recovery partition of the default OS. For example, if your Mac came preloaded with OS X Mountain Lion, then the recovery partition will also be Mountain Lion recovery.
If you upgrade from Mountain Lion to Mavericks using the installer from Mac App Store, the installer will automatically update the recovery partition into Mavericks recovery. However, if your Mac machine did not come preloaded with Mavericks and you choose to install Mavericks from fresh install (using bootable USB installer), there is a chance that your recovery partition will remain Lion recovery or Mountain Lion recovery (depending on the OS X preloaded when you purchased the computer).
After installing OS X Mavericks using fresh install (not upgrading from Lion or Mountain Lion), the OS will check whether the recovery partition matches the version of the OS or not. When you open Mac App Store and check software update, there’s a chance you will see an update called “Mavericks Developer Preview Recovery Update” version 1.0.
What is this update? We think we already install the final version of OS X Mavericks, why do it ask us to install an update from Developer Preview?
This update is actually an update to upgrade your recovery partition from Lion recovery or Mountain Lion recovery to Mavericks recovery. The download size is something around 340 MB, about the size of the Base System of OS X installer. So go ahead and install it, should be reasonably safe. Just a bad naming from Apple.
My Mac mini originally came with Mountain Lion 10.8.2 pre-installed. When I boot the machine while holding OPTION key, it will show Recovery 10.8 2. After I install Mavericks Developer Preview Recovery Update, now it shows Recovery 10.9. There are a LOT of guides in various blogs and forums about how to upgrade or fix this recovery partition. Some people even making their own scripts to do the update. Installing this software update from Apple itself should be an easier step.
Thank you very much! I actually would expect such an information to come directly from Apple and be included in the info about the package in the update window, but thanks anyway!