---
last_verified: 2026-03-14
service: Exadata Cloud Service (ExaCS)
category: database
oci_color: "#AA643B"
---

what: Full Oracle Exadata system in OCI. Provides OS access, RAC, full DBA control
  with cloud elasticity. Runs the same Exadata software as on-prem.

when_to_use:
  - Need OS-level access for custom agents, scripts, or compliance tools
  - RAC required for application architecture
  - Sustained high OCPU workloads (>128 OCPUs)
  - Lift-and-shift from on-prem Exadata with minimal changes
  - Need custom database parameters not available in ADB
  - Applications that use features incompatible with ADB (e.g., dblinks to non-Oracle)

when_NOT_to_use:
  - Small/medium workloads (over-provisioned)
  - No DBA team (ExaCS requires database administration)
  - Variable workloads that benefit from ADB auto-scaling
  - Budget-constrained (high minimum commitment)

limits:
  shapes:
    - name: "Exadata.Quarter3.100"
      base_ocpu: 100
      max_ocpu: 100
      storage_tb: 49.5
    - name: "Exadata.Half3.200"
      base_ocpu: 200
      max_ocpu: 200
      storage_tb: 99
    - name: "Exadata.Full3.400"
      base_ocpu: 400
      max_ocpu: 400
      storage_tb: 198
  max_vm_clusters: 8
  max_databases_per_cluster: "Limited by resources"
  max_pdb_per_cdb: 252

features:
  os_access: true
  rac: true
  data_guard: true
  cross_region_data_guard: true
  custom_db_home: true
  custom_patches: true
  grid_infrastructure: true
  flash_cache: true
  smart_scan: true
  storage_compression: true
  hybrid_columnar_compression: true

ha_dr:
  local_ha: "RAC across Exadata nodes, automatic failover"
  data_guard:
    same_region: "Synchronous, automatic failover with FSFO"
    cross_region: "Asynchronous or far-sync, manual or automatic failover"

sizing_rules:
  minimum: "Quarter rack (100 OCPUs base)"
  scaling: "Can enable additional OCPUs in increments"
  storage: "Comes with infrastructure, expandable"

pricing:
  model: infrastructure_plus_ocpu
  infrastructure_monthly: "Fixed per shape"
  enabled_ocpu_per_hour: 0.336  # approximate
  byol_ocpu_per_hour: 0.168
  notes:
    - "Infrastructure cost is fixed per shape"
    - "Only enabled OCPUs are billed"
    - "BYOL provides ~50% discount on OCPU portion"
    - "Storage included with infrastructure"

gotchas:
  - id: EXACS-001
    issue: "Provisioning takes hours to days"
    impact: "Cannot provision on-demand like ADB-S"
    recommendation: "Plan capacity well in advance"
  - id: EXACS-002
    issue: "Minimum quarter rack commitment"
    impact: "Significant base cost even at low utilization"
    recommendation: "Ensure sustained usage justifies the infrastructure cost"
  - id: EXACS-003
    issue: "DBA team required for ongoing operations"
    impact: "Patching, tuning, and maintenance are customer responsibility"
    recommendation: "Ensure DBA team capacity before choosing ExaCS over ADB"
  - id: EXACS-004
    issue: "Scale-down requires VM cluster modification"
    impact: "Not as elastic as ADB-S for variable workloads"
    recommendation: "Right-size for steady-state, not peak"

migration_tools:
  - name: Oracle Data Guard
    use_for: "On-prem Exadata to ExaCS with minimal downtime"
  - name: RMAN Restore
    use_for: "Backup-based migration with planned downtime"
  - name: Zero Downtime Migration (ZDM)
    use_for: "Automated physical migration"