"Dependency failed for /storage/seat" message and vCenter Server boots in emergency mode following reboot

Products

• VMware vCenter Server

Issue/Introduction

Symptoms:

• The vCenter Server Virtual Machine console shows the following failures after an update to 8.0U2:
  
  Failed to start File System-xxxx
Dependency failed for /storage/seat
Dependency failed for Local File Systems
You are in emergency mode. After logging in, type "journalctl -xb" to view system logs, "system reboot" to reboot, "systemctl default" or "exit" to boot into default mode.
  
  
• Attempting to repair the filesystems by following the steps in Manually running fsck on vCenter Server Appliance 6.5, 6.7, 7.x, 8.x does not resolve the issue.

Environment

vCenter Server 8.x
vCenter Server 9.x

Resolution

Before proceeding, take a snapshot or backup of the affected virtual appliance.

1. 1. 1. Reboot the virtual appliance, and immediately after the OS starts, press e to open the GNU GRUB Edit Menu.
      2. Locate the line that begins with the word linux.
      3. At the end of the line, add "systemd.unit=emergency.target"
         •   Example:                                                                                                                                                                                                                                                     
      4. Press F10 to continue booting.
      5. Remount the root partition by running the following command:
         • mount -o remount,rw /
      6. Find the rogue LVM snaps that were not cleaned up during the update process by running this command:
         • lvscan
         • Note: You should see a list of the original and snapshot logical volumes
         • Example:
           
      7. Run the following command against all of the listed LVM snapshots to remove them:
         • lvremove <LVM Volume>
         • Example:
           
      8. Power off the virtual appliance.
      9. Power on the virtual appliance.

Additional Information

In some scenarios, vCenter continues to boot into emergency mode even after modifying the GRUB boot parameters 

The following steps were attempted as per KB: Manually running a filesystem check
Rebooted the appliance and accessed the GRUB menu.
Appended systemd.unit=emergency.target  to the kernel line.
Pressed F10 to initiate boot 
Despite these changes, the appliance repeatedly enters emergency mode. Upon each boot, root access is required to investigate further.
Once in emergency mode:
Ran journalctl from root of vCenter , to identify the failing partition.
Found /dev/vg_root_0/lv_root_0 as the affected volume.
Executed filesystem repair using below commands as described in resolution section.

fsck -fy /dev/vg_root_0/lv_root_0

or

e2fsck -y /dev/vg_root_0/lv_root_0

Rebooted the appliance after repair to resolve the issue.
The appliance may reboot multiple times during this process as it resolves underlying filesystem issues.

Reference:

Failed to start file system check on /dev/vg_root_0/lv_root0

If none of the steps works, revert to a known good snapshot to recover or restore from a backup.