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Remediation

Prerequisites​

  • Ensure you have sufficient quotas in the destination region (disk, snapshot, VM quotas).
  • Verify that persistent disks attached to the VM are not currently mounted elsewhere.
  • Consider local SSDs or ephemeral storage: data on local SSDs will not survive termination, so replicate or back up any needed data.
  • If the VM has GPUs, ensure equivalent GPU types are available in the target region/zone.
  • If moving across regions, you may need to choose a new subnetwork in the target region (cross-region VMs cannot keep existing subnetworks).
  • Recognize that internal/external IPs may change. Intra-region moves preserve external IPs; cross-region moves require new external IPs.

Migrate a Google GCE Instance​

1. Identify Disks Associated with the Instance​

gcloud compute instances describe {{instance-name}} \
  --zone {{old-zone}} \
  --format="list(name,status,disks)"

2. Disable Auto-Delete on Disks​

Prevent the disks from being deleted when the VM is removed:

gcloud compute instances set-disk-auto-delete {{instance-name}} \
  --zone {{old-zone}} \
  --disk {{boot-disk}} --no-auto-delete

gcloud compute instances set-disk-auto-delete {{instance-name}} \
  --zone {{old-zone}} \
  --disk {{data-disk}} --no-auto-delete

3. (Optional) Save VM Metadata​

Export VM metadata to a file so it can be reapplied later:

gcloud compute instances describe {{instance-name}} \
  --zone {{old-zone}} > {{instance-name}}.describe

4. Create Backup Snapshots​

Create initial backup snapshots of the disks:

gcloud compute disks snapshot {{boot-disk}} {{data-disk}} \
  --snapshot-names {{backup-boot-disk}},{{backup-data-disk}} \
  --zone {{old-zone}}

5. Delete the VM​

Stop and delete the VM (disks are preserved because auto-delete was disabled):

gcloud compute instances delete {{instance-name}} \
  --zone {{old-zone}}

6. Create Final Snapshots​

Create new snapshots after deletion:

gcloud compute disks snapshot {{boot-disk}} {{data-disk}} \
  --snapshot-names {{snapshot-boot-disk}},{{snapshot-data-disk}} \
  --zone {{old-zone}}

7. Delete Old Disks​

If you plan to reuse the same disk names, delete the original disks:

gcloud compute disks delete {{boot-disk}} {{data-disk}} \
  --zone {{old-zone}}

8. Create New Disks in Target Zone​

Create new persistent disks in {{new-zone}} from snapshots:

gcloud compute disks create {{boot-disk}} \
  --source-snapshot {{snapshot-boot-disk}} \
  --zone {{new-zone}}

gcloud compute disks create {{data-disk}} \
  --source-snapshot {{snapshot-data-disk}} \
  --zone {{new-zone}}

9. Recreate the VM in the Target Zone​

Recreate the VM and attach the new disks:

gcloud compute instances create {{instance-name}} \
  --machine-type n1-standard-4 \
  --zone {{new-zone}} \
  --disk name={{boot-disk}},boot=yes,mode=rw \
  --disk name={{data-disk}},mode=rw

10. (Optional) Delete Temporary Snapshots​

Clean up snapshots to reduce storage costs:

gcloud compute snapshots delete {{snapshot-boot-disk}} {{snapshot-data-disk}}
gcloud compute snapshots delete {{backup-boot-disk}} {{backup-data-disk}}