What's in an HA system?

• Membership services

• Communication services

• Cluster "manager"

• Resource Monitoring

• Storage

  • Journalling Filesystem
  • (or) Cluster Filesystem
  • Volume Manager (with snapshots)
  • (either) Shared Storage (SCSI or FC)
  • (or) Replicated Storage (DRBD, NBD, etc.)

• Resource (I/O) Fencing

Notes: