# OCI Service: Exadata Cloud Service (ExaCS)
# Last verified: 2026-03

service:
  name: "Exadata Cloud Service (ExaCS)"
  id: exacs
  category: database
  color: "#AA643B"

description: "Dedicated Exadata infrastructure running in OCI, providing the full performance and isolation of Exadata hardware with cloud elasticity. Supports Oracle RAC, Data Guard, and direct OS/CDB-level access for maximum DBA control."

when_to_use:
  - "Oracle RAC workloads requiring multi-node clustering"
  - "Regulatory or compliance scenarios demanding dedicated infrastructure isolation"
  - "High IOPS / low-latency database workloads (OLTP or mixed)"
  - "Sustained compute needs exceeding 128 OCPUs"
  - "Need direct OS-level or CDB-level access for custom patching, tuning, or agents"

when_not_to_use:
  - "Small workloads under 16 OCPUs — use Autonomous Database Serverless (ADB-S) or Base Database Service"
  - "No dedicated DBA team to manage patching, RAC, and infrastructure"
  - "Simple OLTP with no RAC or isolation requirements — use ADB-S instead"
  - "Dev/test environments where cost efficiency matters more than performance"

variants:
  - id: exacs_x9m
    name: "ExaCS X9M"
    description: "Exadata X9M shape — current-generation infrastructure with RDMA over Converged Ethernet and persistent memory acceleration."
    per_db_server:
      ocpus: 126
      memory_gb: 1390
      pmem_tb: 1.5
      flash_cache_tb: 25.6
    per_storage_server:
      usable_tb: 63.6
  - id: exacs_x11m
    name: "ExaCS X11M"
    description: "Exadata X11M shape — latest generation with AMD EPYC 9J25 processors and XRMEM acceleration."
    per_db_server:
      ecpus: 760
      memory_gb: 1390
      xrmem_gb: 1250
      flash_cache_tb: 27.2
    per_storage_server:
      usable_tb: 52.5
      type: "Extreme Flash (EF)"

sizing:
  model: "Elastic per-server (2-32 DB servers, 3-64 storage servers)"
  rack_configurations:
    quarter_rack:
      ocpus: "252 (X9M: 2 × 126/server)"
      memory: "2.71 TB (X9M: 2 × 1,390 GB)"
      storage: "Up to 190.8 TB usable (X9M: 3 SS × 63.6 TB)"
      db_nodes: 2
      storage_servers: 3
    half_rack:
      ocpus: "504 (X9M: 4 × 126/server)"
      memory: "5.43 TB"
      storage: "Up to 383 TB usable"
      db_nodes: 4
      storage_servers: 6
    full_rack:
      ocpus: "1,008 (X9M: 8 × 126/server)"
      memory: "10.86 TB"
      storage: "Up to 766 TB usable"
      db_nodes: 8
      storage_servers: 12
  legacy_x8_fixed_shapes:
    quarter_rack:
      storage_tb: 149
    half_rack:
      storage_tb: 299
    full_rack:
      storage_tb: 598
    notes: "X8 shapes are fixed-size (not elastic). Storage values are usable disk, not flash cache."
  ocpu_scaling: "OCPUs can be scaled online in increments without downtime. You pay for enabled OCPUs, not the total available in the rack."
  sizing_guidance: "Start with a quarter rack for most production workloads. Scale OCPUs on demand. Choose half/full rack only when storage capacity or aggregate memory requirements exceed quarter rack limits."

gotchas:
  - id: exacs_minimum_cost
    severity: HIGH
    description: "Minimum infrastructure cost is approximately $6,000+/month for a quarter rack, regardless of OCPU usage. Ensure sustained workload justifies the commitment."

  - id: exacs_provisioning_time
    severity: MEDIUM
    description: "Exadata infrastructure provisioning takes 4-8 hours. Plan deployments accordingly — this is not an instant resource like a Compute VM."

  - id: exacs_patching_window
    severity: MEDIUM
    description: "Patching requires a scheduled maintenance window. Database nodes are patched in a rolling fashion but plan for reduced capacity during the process."

  - id: exacs_gi_db_patch_separate
    severity: MEDIUM
    description: "Grid Infrastructure (GI) and Database Home patches are applied separately and may have different schedules. Coordinate both to avoid version skew."

  - id: exacs_overprovisioning_risk
    severity: HIGH
    description: "Customers frequently over-provision by choosing half or full racks when a quarter rack with OCPU scaling would suffice. Always validate actual IOPS and CPU requirements before sizing up."

  - id: exacs_network_placement
    severity: LOW
    description: "ExaCS requires placement in a private subnet with sufficient IP addresses. Each DB node and each virtual IP consumes an IP; plan your subnet CIDR accordingly."

implied_dependencies:
  - service: vcn
    reason: "ExaCS infrastructure must be deployed in a VCN"
  - service: private_subnet
    reason: "DB nodes and SCAN listeners require private subnet placement"
  - service: service_gateway
    reason: "Access to OCI object storage for backups and patching from private subnets"
  - service: oci_vault
    reason: "TDE wallet management and encryption key storage"

competitive_notes:
  vs_aws: "AWS has no equivalent dedicated Oracle Exadata infrastructure offering. RDS Oracle and RDS Custom lack RAC support and Exadata storage acceleration. Customers needing true Exadata performance have no AWS-native path."

references:
  documentation: "https://docs.oracle.com/en-us/iaas/Content/Database/Concepts/exaoverview.htm"
  pricing: "https://www.oracle.com/cloud/price-list/#exadata"

changelog:
  - date: "2026-03-14"
    contributor: { name: "Diego Cabrera", team: "Field Architecture" }
    change: "Initial creation with shapes, sizing, gotchas, dependencies"