Introduction

Vault's integrated Raft storage backend provides high availability by replicating data across multiple nodes. When disaster recovery is needed, a Raft snapshot can be restored to rebuild the cluster. However, snapshot restore can fail due to snapshot file corruption, Vault version mismatch, insufficient disk space, or conflicting Raft state on the target node.

Symptoms

  • vault operator raft snapshot restore fails with error message
  • Restore command hangs indefinitely during the snapshot application phase
  • Target node crashes after initiating snapshot restore
  • Raft peer list is empty after restore, preventing cluster reformation
  • Error message: failed to restore snapshot: snapshot version mismatch or Raft log corrupted

Common Causes

  • Snapshot file corrupted during transfer or storage
  • Vault version on the restore target differs from the version that created the snapshot
  • Insufficient disk space on the target node to extract and apply the snapshot
  • Existing Raft state on the target node conflicting with the snapshot data
  • Snapshot taken from a different Vault cluster with incompatible configuration

Step-by-Step Fix

  1. 1.Verify the snapshot file integrity: Check the snapshot is not corrupted.
  2. 2.```bash
  3. 3.ls -lh vault-snapshot.snap
  4. 4.# Verify file size matches the source
  5. 5.vault operator raft snapshot inspect vault-snapshot.snap
  6. 6.`
  7. 7.Stop all Vault nodes before restoring: Ensure a clean restore state.
  8. 8.```bash
  9. 9.systemctl stop vault
  10. 10.# On all nodes
  11. 11.`
  12. 12.Clear existing Raft state on the target node: Remove conflicting data.
  13. 13.```bash
  14. 14.rm -rf /opt/vault/data/raft/
  15. 15.mkdir -p /opt/vault/data/raft
  16. 16.chown vault:vault /opt/vault/data/raft
  17. 17.`
  18. 18.Restore the snapshot on a single node: Start with one node first.
  19. 19.```bash
  20. 20.vault operator raft snapshot restore vault-snapshot.snap \
  21. 21.-force \
  22. 22.-addr="https://vault-1:8200"
  23. 23.`
  24. 24.Start Vault and rejoin remaining nodes: Rebuild the HA cluster.
  25. 25.```bash
  26. 26.systemctl start vault
  27. 27.# Unseal the node
  28. 28.vault operator unseal <key-1>
  29. 29.vault operator unseal <key-2>
  30. 30.vault operator unseal <key-3>
  31. 31.# Join remaining nodes
  32. 32.vault operator raft join https://vault-2:8200
  33. 33.vault operator raft join https://vault-3:8200
  34. 34.`

Prevention

  • Verify snapshot integrity with vault operator raft snapshot inspect before any restore attempt
  • Ensure all Vault nodes run the same version before creating snapshots
  • Store snapshots in multiple locations (S3, GCS, local) with checksum verification
  • Test snapshot restore procedures regularly in a staging environment
  • Monitor Raft replication lag and alert on nodes falling behind
  • Maintain a documented disaster recovery runbook with snapshot restore steps
  • Size disk to accommodate at least 2x the current Raft data size for snapshot operations