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oci-deal-accelerator/kb/diagram/assets/archcenter-refs/dr-active-dg-farsync-db-at-aws/_description.md
root b30a4f0d32 Diagram generation: ref-arch-driven procedure + spec validator + KB enrichment 
The diagram path now follows a documented standard procedure (lookup
the closest Oracle Architecture Center reference → confirm components
→ author absolute_layout → spec validator → render → visually verify)
and ships persistent guardrails so layout regressions can't recur.

Persistent procedure changes (apply to all users, all sessions):
- tools/diagram_spec_validator.py — geometry checks (CONTAINER_TOO_THIN,
  CONTAINER_PADDING_VIOLATION, LABEL_OVERFLOW_PARENT) run BEFORE either
  renderer (drawio + PPTX). Catches the subnet-collapse / label-overflow
  bugs that the post-render drawio validator missed.
- tools/oci_diagram_gen.py + tools/oci_pptx_diagram_gen.py — call the
  spec validator before emitting any output. Adds mysql / mysql_heatwave
  type aliases.
- tools/archcenter_pattern_lookup.py — scores against cached page
  descriptions (not just the 1-line summary), supports --queries for
  multi-fragment composition, and applies synonym expansion via
  kb/architecture-center/synonyms.yaml so "LB HA cross AD" matches
  "load balancer high availability availability domain".
- kb/architecture-center/synonyms.yaml — canonical synonym table
  (load balancer, autonomous database, data guard, …) used by the
  lookup scorer.

KB enrichment:
- tools/archcenter_description_fetcher.py + 121 cached _description.md
  under kb/diagram/assets/archcenter-refs/<slug>/. Removes the runtime
  dependency on docs.oracle.com when authoring specs and feeds the
  pattern-lookup scorer.
- 110+ cached .drawio / .svg / .png references for offline reuse,
  plus the OCI Toolkit v24.2 import (kb/diagram/assets/oci-toolkit-drawio).

Documentation:
- docs/skill/output-formats.md — new "Standard diagram-generation
  procedure (MANDATORY)" + geometry rules + the new validator entry.
- SKILL.md option 2 — references the mandatory procedure.
- README.md — describes the spec validator, archcenter_pattern_lookup
  and description fetcher, and updates the KB-health table.

Tooling that backs the procedure (cumulative across recent sessions):
tools/archcenter_case_runner.py, archcenter_batch_driver.py,
archcenter_zip_downloader.py, drawio_visual_validator.py,
drawio_fidelity_eval.py, harvest_drawio_icon.py, import_oci_library.py,
oci_pptx_diagram_gen.py, oci_pptx_render.py, refresh_pptx_icon_index.py.

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>
2026-04-25 21:15:21 -03:00

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Deploy Active Data Guard Far Sync to protect data across Oracle Database@AWS regions

Summary (catalog)

Far Sync instance for zero data loss protection across AWS regions. Synchronous redo to local Far Sync, asynchronous to remote standby. Requires cross-region AWS networking for redo transport.

Architecture (fetched from source)

Architecture

The following architecture shows a cross-region disaster recovery with Active Data Guard Far Sync with two Far Sync instances running in each OCI region:

Description of the illustration cross-region-dr-activedg-farsync.png

cross-region-dr-activedg-farsync-oracle.zip

Two Active Data Guard Far Sync instances are created in the corresponding Oracle Cloud Infrastructure (OCI) regions. The Primary database in Region 1 sends the redo data in SYNC mode to the local Far Sync instance in the same region, which forwards the redo data in ASYNC mode to the standby database in the remote Region 2.

After a role switch and the database in Region 2 becomes the primary, it sends the redo data in SYNC mode to its local Far Sync instance in the same region, which forwards the redo data in ASYNC mode to the standby database in the remote Region 1.

The Oracle Exadata Database Service on Oracle Database@AWS network is connected to the Exadata client subnet using a Dynamic Routing Gateway (DRG) managed by Oracle. A DRG is also required to create a peer connection between VCNs in different regions. Because only one DRG is allowed per VCN in OCI, a second VCN with its own DRG is required to connect the primary and standby VCNs in each region.

The application is replicated across regions to access the database in the same region and achieve the lowest latency and highest performance.

This architecture supports the following components:

  • AWS region AWS regions are separate geographic areas. They consist of multiple, physically separated, and isolated availability zones that are connected with low latency, high throughput, highly redundant networking.

  • AWS availability zone Availability zones are highly available data centers within each AWS region.

  • OCI virtual cloud network and subnet A virtual cloud network (VCN) is a customizable, software-defined network that you set up in an OCI region. Like traditional data center networks, VCNs give you control over your network environment. A VCN can have multiple non-overlapping classless inter-domain routing (CIDR) blocks that you can change after you create the VCN. You can segment a VCN into subnets, which can be scoped to a region or to an availability domain. Each subnet consists of a contiguous range of addresses that don't overlap with the other subnets in the VCN. You can change the size of a subnet after creation. A subnet can be public or private.

  • Route table Virtual route tables contain rules to route traffic from subnets to destinations outside a VCN, typically through gateways.

  • Network security group (NSG) NSGs act as virtual firewalls for your cloud resources. With the zero-trust security model of OCI you control the network traffic inside a VCN. An NSG consists of a set of ingress and egress security rules that apply to only a specified set of virtual network interface cards (VNICs) in a single VCN.

  • Local peering Local peering allows two VCNs within the same OCI region to communicate directly using private IP addresses. This communication does not traverse the internet or your on-premises network. Local peering is enabled by a Local Peering Gateway (LPG), which serves as the connection point between VCNs. Configure an LPG in each VCN and establish a peering relationship to allow instances, load balancers, and other resources in one VCN to securely access resources in another VCN within the same region.

  • Dynamic routing gateway (DRG) The DRG is a virtual router that provides a path for private network traffic between VCNs in the same region, between a VCN and a network outside the region, such as a VCN in another OCI region, an on-premises network, or a network in another cloud provider.

  • Remote peering Remote peering enables private communication between resources in different VCNs, which can be located in the same or different OCI regions. Each VCN uses its own Dynamic Routing Gateway (DRG) for remote peering. The DRGs securely route traffic between the VCNs over OCI's private backbone, allowing resources to communicate using private IP addresses without routing traffic over the internet or through on-premises networks. Remote peering removes the need for internet gateways or public IP addresses for instances that need to connect across regions.

  • Oracle Exadata Database Service on Dedicated Infrastructure Oracle Exadata Database Service on Dedicated Infrastructure enables you to leverage the power of Exadata in the cloud. Oracle Exadata Database Service delivers proven Oracle Database capabilities on purpose-built, optimized Oracle Exadata infrastructure in the public cloud. Built-in cloud automation, elastic resource scaling, security, and fast performance for all Oracle Database workloads helps you simplify management and reduce costs.

  • Oracle Data Guard Oracle Data Guard and Active Data Guard provide a comprehensive set of services that create, maintain, manage, and monitor one or more standby databases and that enable production Oracle databases to remain available without interruption. Oracle Data Guard maintains these standby databases as copies of the production database by using in-memory replication. If the production database becomes unavailable due to a planned or an unplanned outage, Oracle Data Guard can switch any standby database to the production role, minimizing the downtime associated with the outage. Oracle Active Data Guard provides the additional ability to offload read-mostly workloads to standby databases and also provides advanced data protection features.

  • Active Data Guard Far Sync Active Data Guard Far Sync is a lightweight Oracle database instance that receives redo data synchronously from the primary database and forwards it asynchronously to one or more standby databases. It ensures zero data loss at any distance with minimal impact on the primary database performance without requiring a local synchronous standby database.

Recommendations

Use the following recommendations as a starting point. Your requirements might differ from the architecture described here.

  • Place Far Sync far enough from the primary database to avoid common‑cause failures but close enough to minimize latency.

  • Deploy two Far Sync instances per region for high availability. If all Far Sync instances in the primary region are unavailable, Active Data Guard redo will be shipped directly to the remote standby in ASYNC mode. This removes zero‑data‑loss protection and can introduce transport lag, impacting Recovery Point Objectives (RPOs).

  • Ensure storage performance for Far Sync is adequate to sustain redo write IOPS comparable to or better than the primary database's online redo logs.

  • Configure Active Data Guard across regions for the databases provisioned in the Exadata VM cluster on Oracle Database@AWS by using an OCI Managed network.

Considerations for Cross-Region Disaster Recovery

When performing cross-region disaster recovery for Oracle Exadata Database Service on Oracle Database@AWS , consider the following:

  • Configure OCI as the preferred network for better performance, lower latency, higher throughput, and reduced cost; the first 10 TB/month of data egress is free across regions.

  • Although Far Sync is lightweight, disk performance is critical because it must persist redo before acknowledging commits to the primary database, which if undersized can affect application latency.

  • Network performance of the Far Sync instance is critical for heavy workloads.

  • With multiple standby databases and Far Sync instances, the configuration can get complicated. Use the Active Data Guard broker RedoRoutes property to simplify the definition of how redo is transported to the various dest

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