Troubleshooting Failed VM Boot After Disaster Recovery Failover

Products

• VMware vSAN

Issue/Introduction

After performing a disaster recovery (DR) failover, some virtual machines (VMs) may fail to boot properly. This article provides steps to diagnose and resolve VM boot failures in a post-DR failover scenario.

Environment

- vSphere environment
- Disaster Recovery setup (using replication technologies like Zerto, VMware SRM, etc.)
- Applicable to various guest operating systems

Cause

VM boot failures after DR failover can occur due to multiple factors:
1. Incomplete or corrupted VM replication
2. Storage connectivity issues in the DR site
3. Network configuration mismatches
4. Guest operating system boot problems
5. VM hardware compatibility issues

Resolution

1. Verify VM replication status:
   a. Check replication logs for any errors or warnings
   b. Ensure all VM files were successfully replicated to the DR site

2. Examine VM configuration:
   a. Open the vSphere Client and navigate to the affected VM
   b. Review VM settings, focusing on storage and network configurations
   c. Verify that all required virtual disks are present and accessible

3. Check storage connectivity:
   a. Confirm that all necessary datastores are available in the DR site
   b. Verify that the ESXi hosts have proper access to the storage

4. Inspect network settings:
   a. Review the VM's network adapter settings
   b. Ensure that the assigned network in the DR site is correct and operational

5. Analyze VM console output:
   a. Open the VM console in the vSphere Client
   b. Observe the boot process and note any error messages
   c. If the VM is stuck at a BIOS-like screen, this may indicate a guest OS issue

6. Try forced VM boot options:
   a. Power off the VM
   b. Edit VM settings and select "Boot Options"
   c. Enable "Force BIOS setup" and power on the VM
   d. If successful, reconfigure BIOS settings as needed and attempt normal boot

7. Check VM hardware compatibility:
   a. Verify that the VM hardware version is compatible with the DR site's ESXi version
   b. Upgrade VM hardware if necessary (caution: ensure guest OS support before upgrading)

8. Attempt guest OS repair:
   a. If the guest OS is accessible, use built-in repair tools (e.g., Windows Startup Repair)
   b. For severe cases, consider attaching the VM's virtual disk to a working VM for file recovery

9. Recreate VM configuration:
   a. If all else fails, create a new VM with the same specifications
   b. Attach the existing virtual disks to the new VM
   c. Attempt to boot the new VM configuration

Additional Information

VM hardware compatibility links:
- Hardware Features Available with Virtual Machine Compatibility Settings