If running the esxcfg-boot -b command fails, run vdf -h on the host to see how much free space is available in /boot. If there is very little space, such as 100 MB or less, check the /tmp and /vmimages folder for any old files or very large ISOs and remove them. Re-run esxcfg-boot -b. If you are able to run this command, reboot the host.
Note: ESX requires at least 24MB to boot properly.
You may also experience this issue after a successful upgrade, such as upgrading from ESX 3.5 to 4.0 and then performing an upgrade from 4.0 to 4.1. To resolve this issue, go to the troubleshooting mode and then run this command to clean the old ESX 3.5.x files:
cleanup-esx3 –f
Note: After you use this command, you cannot revert to ESX 3.5.x.
For more information on troubleshooting this issue, see Troubleshooting an ESX host that does not boot (10065).
For ESX 4.x, check the /boot/trouble directory for any files that may be present and remove them to free up space:
To remove files from the /boot/trouble directory, run these commands:#cd /boot/trouble
#ls
initrd.img vmlinuz
#rm -r * Note: VMware High Availability agents may not correctly configure after the failure to boot and in the Summary tab, you can see that the HA configuration failed. In this case, in vCenter Server, right-click the host and click Reconfigure HA.
ESX/ESXi host fails to boot after installation or upgrade