ESXi host loses complete or partial configuration after a reboot
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ESXi host loses complete or partial configuration after a reboot

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Article ID: 306902

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Updated On:

Products

VMware vSphere ESXi

Issue/Introduction

This article provides information about:
  • The ESXi boot process
  • The impact of an unclean shutdown or reboot



Symptoms:

  • ESXi host loses complete or partial configuration after a reboot



Environment

VMware vSphere ESXi 

Cause

This issue can occur after an unclean shutdown or reboot.

Resolution

These steps outline the process for saving configuration settings. Interruption during the process can lead to a loss of configuration settings.
  1. auto-backup.sh, a cronjob that is executed the first minute of every hour, saves the configuration state of the ESXi host.
  2. All configurations modifications are primarily written to /bootbank.
  3. In the event of VIB updates/installation the operating system related binaries and configuration files are copied over to /altbootbank.

    Note: Silent VIB updates may occur. You can validate if these have occurred using Log -/var/log/esxupdate.log and the configuration file in bootbank or altbootbankboot.cfg.
     
  4. Configuration files are saved in the file state.tgz.
  5. A known good state is saved in /bootbank prior to the update.
  6. If there have been updates/installations, on a subsequent reboot, ESXi boots off /altbootbank from the saved/modified state. This is achieved by updating boot.cfg file.
    • /bootbank/boot.cfg : bootstate=0 (normal state), updated=1 (initial install)
    • /altbootbank/boot.cfg : bootstate=1 (updating state), updated=2 (incremented)
  7. Early in the boot process, the higher value for bootstate is chosen from the two bootbanks. Later in the boot process, the symbolic link /bootbank is created to point to the bootbank the host booted from, and /altbootbank is created to point to the secondary bootbank. The two bootbanks swap their name on the first boot after an upgrade. 
  8. At the end of the boot process,the jumpstart script resets the bootstate to 0.
  9. If the host is rebooted recursively or the reboot process is interrupted, the ESX host boots into the previous state, causing the differential configuration of bootbank and altbootbank to be lost.



Additional Information

Impact/Risks: