Introduction VM live migration failures during infrastructure maintenance force planned downtime instead of zero-downtime transitions. This is critical when migrating hosts for hardware upgrades or patching.

Symptoms - Migration tool: "Live migration failed" - Error: "Migration aborted: destination host incompatible" - VM downtime during migration (should be seamless) - Error: "Insufficient resources on destination host" - Migration starts but rolls back midway

Common Causes - CPU incompatibility between source and destination hosts - Shared storage not accessible from destination - Network configuration mismatch - Insufficient memory on destination host - VM using features not supported on destination (GPU, passthrough)

Step-by-Step Fix 1. **Check migration compatibility': ```bash # vSphere vim-cmd hostsvc/motion_compatibility_check <vm-id> # Proxmox qm migrate <vmid> <target-node> --online ```

  1. 1.**Check resource availability on destination':
  2. 2.```bash
  3. 3.# Verify memory, CPU, and storage
  4. 4.free -h
  5. 5.nproc
  6. 6.df -h /var/lib/vz
  7. 7.`
  8. 8.**Use storage migration if storage is incompatible':
  9. 9.```bash
  10. 10.# VMware
  11. 11.svmotion --vm <vm-name> --datastore <target-datastore>
  12. 12.# Proxmox
  13. 13.qm move_disk <vmid> <disk> <target-storage>
  14. 14.`

Prevention - Test migration compatibility before scheduling - Ensure shared storage is accessible from all hosts - Use homogeneous hardware clusters for easier migration - Monitor resource availability before migration - Have rollback plan for failed migrations