The following error appears when booting to a NetBoot image:
“Startup Disk is Almost Full”
Explanation
This error occurs when the minimal base OS image that was used to create a NetBoot image with Apple System Image Utility is too small, preventing certain applications from being able to run.
This often occurs if you used Composer to create the minimal base OS image. Since Composer removes virtual memory swap files, NetBoot recreates these files, which can fill up the boot volume.
Resolution
You can make the NetBoot image larger by executing:
sudo hdiutil resize -size 10G /path/to/NetBoot/image/file
Note: 10G is just a suggestion. This size may vary depending the amount of space available on the server and the amount of space you need to run the necessary applications.
Note: The default path to the NetBoot image file is /Library/NetBoot/NetBootSP0/ImageName.nbi/NetBoot.dmg