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kb/patterns/database-ha/active-data-guard.yaml

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+# Pattern: Active Data Guard HA/DR
+# Composable architecture block for Oracle Database high availability
+
+pattern:
+  name: "Active Data Guard"
+  id: active_data_guard
+  category: database-ha
+  applies_to: [adb_s, adb_d, dbcs, exacs]
+
+description: |
+  Oracle Active Data Guard provides real-time data protection with a standby database
+  that can be used for read-only queries, reporting, and backups while maintaining
+  synchronous or asynchronous replication from the primary.
+
+variants:
+  - id: adg_same_region
+    name: "Same-Region ADG (HA)"
+    topology: "Primary + Standby in same region, different ADs or FDs"
+    rpo: "0 (synchronous)"
+    rto: "< 30 seconds (automatic failover with FSFO)"
+    use_when:
+      - "99.99% SLA requirement"
+      - "Zero RPO mandatory"
+      - "Read-only offload needed"
+
+  - id: adg_cross_region
+    name: "Cross-Region ADG (DR)"
+    topology: "Primary in Region A, Standby in Region B"
+    rpo: "> 0 (asynchronous, typically seconds to minutes)"
+    rto: "Minutes to 1 hour depending on automation"
+    use_when:
+      - "Regional disaster recovery required"
+      - "RPO of seconds acceptable"
+      - "Regulatory requirement for geo-separation"
+
+  - id: adg_hybrid
+    name: "Same-Region HA + Cross-Region DR"
+    topology: "Primary + Local Standby (sync) + Remote Standby (async)"
+    rpo: "0 local, seconds remote"
+    rto: "< 30s local, minutes remote"
+    use_when:
+      - "Maximum protection: HA + DR"
+      - "Mission-critical workloads"
+
+preconditions:
+  - "Oracle Database Enterprise Edition with Active Data Guard option"
+  - "BYOL: customer must have ADG license or ULA"
+  - "License Included: ADG included with ADB-S, ExaCS EE-HP/EE-EP"
+  - "For ADB-S: Autonomous Data Guard (managed, no manual config)"
+
+implied_services:
+  - service: data_guard
+  - service: dns_traffic_management
+    reason: "DNS failover for application connection string update"
+    when: "cross_region"
+  - service: oci_notifications
+    reason: "Alert on failover events"
+
+conflicts:
+  - pattern: "backup_restore_only"
+    reason: "ADG provides real-time replication; backup-restore is a subset"
+
+cost_impact:
+  - "Standby database incurs full compute + storage cost"
+  - "For ADB-S: standby OCPUs billed at same rate"
+  - "Cross-region: additional network egress for redo transport"
+  - "BYOL: ADG license required (included in EE-EP)"
+
+sizing_rules:
+  - "Standby must be same shape/OCPU as primary for failover"
+  - "For read-only offload: standby can handle ~80% of primary read capacity"
+  - "Network bandwidth for redo: estimate 10-50 Mbps per 10K TPS (varies by workload)"
+
+references:
+  - "https://docs.oracle.com/en/cloud/paas/autonomous-database/adbsa/autonomous-data-guard.html"
+  - "https://docs.oracle.com/en/database/oracle/oracle-database/19/sbydb/"

kb/patterns/database-ha/pattern.yaml

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+---
+last_verified: 2026-03-14
+pattern: Database High Availability
+category: database
+---
+
+description: |
+  Patterns for achieving high availability for Oracle databases on OCI.
+  Covers ADB-S, ADB-D, ExaCS, and DBCS configurations.
+
+patterns:
+  adb_s_ha:
+    name: "ADB-S Built-in HA"
+    availability: "99.95% SLA"
+    rto: "<30 seconds"
+    rpo: "0 (synchronous)"
+    components:
+      - "ADB-S with Autonomous Data Guard (same-region)"
+      - "Automatic failover enabled"
+      - "No additional configuration needed"
+    cost_impact: "2x OCPU cost (standby billed at same rate)"
+    when_to_use:
+      - "Standard HA requirement"
+      - "Same-region protection sufficient"
+    notes:
+      - "Standby is provisioned automatically when ADG is enabled"
+      - "Failover is transparent to applications using recommended connection strings"
+      - "Switchover for planned maintenance is automatic"
+
+  adb_s_cross_region:
+    name: "ADB-S Cross-Region ADG"
+    availability: "99.95% SLA per region, survives region failure"
+    rto: "<5 minutes (automatic), <30 minutes (manual)"
+    rpo: "Seconds (asynchronous replication)"
+    components:
+      - "ADB-S primary in Region 1"
+      - "ADB-S standby in Region 2 (cross-region ADG)"
+      - "Optional: Refreshable clone in Region 2 for reporting"
+    cost_impact: "2x OCPU + inter-region data transfer"
+    when_to_use:
+      - "Compliance requires geo-redundant DR"
+      - "RTO < 30 minutes for region failure"
+      - "Business-critical workloads"
+    notes:
+      - "Cross-region ADG is asynchronous — RPO is not zero"
+      - "Automatic failover requires ADG Auto-Failover configuration"
+      - "Test failover quarterly"
+
+  exacs_rac_ha:
+    name: "ExaCS RAC High Availability"
+    availability: "99.95%+ (RAC + Data Guard)"
+    rto: "<60 seconds (RAC failover)"
+    rpo: "0 (synchronous within RAC)"
+    components:
+      - "ExaCS with multi-node RAC"
+      - "Data Guard to standby ExaCS (same or cross-region)"
+      - "Fast-Start Failover (FSFO) with Observer"
+    cost_impact: "2x infrastructure for Data Guard standby"
+    when_to_use:
+      - "Application requires RAC"
+      - "Sub-minute RTO required"
+      - "High-throughput OLTP workloads"
+
+  dbcs_ha:
+    name: "DBCS 2-Node RAC + Data Guard"
+    availability: "99.95%"
+    rto: "<60 seconds (RAC), <5 minutes (Data Guard)"
+    rpo: "0 (synchronous within region)"
+    components:
+      - "DBCS 2-node RAC (primary)"
+      - "DBCS Data Guard standby"
+    cost_impact: "3x compute (2 RAC + 1 DG standby)"
+    when_to_use:
+      - "Moderate workloads needing HA"
+      - "Budget doesn't allow Exadata"
+
+decision_tree: |
+  Need HA for Oracle Database?
+  ├── Using ADB-S?
+  │   ├── Same-region sufficient → Enable ADG (built-in)
+  │   └── Cross-region required → Cross-region ADG
+  ├── Using ExaCS?
+  │   ├── RAC for local HA
+  │   └── Data Guard for DR (same or cross-region)
+  └── Using DBCS?
+      ├── 2-node RAC for local HA
+      └── Data Guard for DR