SAP Cloud: Designing a Cost-Optimized Disaster Recovery on AWS
Cut your SAP Cloud Disaster Recovery costs on AWS by three. Pilot Light strategy, Start/Stop automation and resilient architecture.
The resilience of a brownfield SAP landscape is often perceived as a passive cost center. Maintaining an inactive mirror infrastructure in a secondary region weighs heavily on your IT budgets. In a SAP Cloud environment, the question is no longer just availability. Financial efficiency must become your top priority. A CTO must now arbitrate between recovery time (RTO) and resource optimization. This guide details how to turn your Disaster Recovery (DR) strategy into a savings lever.
SAP Cloud: The financial trap of Brownfield DR
In a brownfield program, the classic mistake is to transpose the existing setup without requalifying the need. The reflex is to duplicate production identically (1:1 ratio). This "Hot Standby" approach ties up expensive EC2 instances unnecessarily. These resources produce no business value 99% of the time. Software licenses and provisioned EBS volumes inflate this static bill. The lack of automation often forces keeping resources running for convenience. Yet over-provisioning is the number one enemy of your cloud profitability. A CTO must distinguish local high availability from regional Disaster Recovery. Mixing these two concepts leads to over-protecting secondary components. The latent cost of active DR then far exceeds the financial risk covered.
Classic approach vs lightweight hybrid DR on AWS
The classic approach favors synchronous HANA replication on active instances. This guarantees near-zero RPO, but at the cost of permanent compute. The optimized architecture relies on the "Pilot Light" or "Lightweight Hybrid" model. Here, only data is replicated via Amazon S3 Cross-Region Replication.
| Characteristic | Classic Approach (Warm Standby) | Hybrid Approach (Pilot Light) |
|---|---|---|
| EC2 Compute | Active instances 24/7 | Instances created via Terraform on demand |
| EBS Storage | Full permanent provisioning | On-demand provisioning via IaC |
| Relative Cost | 80% to 100% of primary site | 20% to 35% of primary site |
| RTO | Very short (minutes) | Moderate (2 to 4 hours) |
For a brownfield SAP landscape, restoration from S3 offers an optimal balance. Using AWS Elastic Disaster Recovery (DRS) effectively protects the application tier. Destination EC2 instances only start in case of an actual disaster. This means you only pay for storage under normal conditions.
How Start/Stop changes the SAP Cloud financial equation
Start/Stop automation is the most immediate lever to reduce costs. On AWS, a stopped EC2 instance only charges for its EBS storage. For non-production environments, the potential savings often reach 60%. Applying this principle to the DR site is a strategic no-brainer. Implementation requires "SAP-aware" tools to guarantee integrity. The "Power Management Tool" recommends orchestration via systemd. HANA must imperatively stop before the OS instance shutdown. Control scripts verify the status of ASCS and PAS processes. A clean shutdown sequence prevents data corruption on restart.
Recommended architecture and SAP Cloud Runbook on AWS
The ideal architecture relies on asynchronous replication and Infrastructure as Code. All SAP servers should reside in a single AWS account and VPC. This simplifies interconnectivity and standardizes security governance. The DR site is thus driven by tested and auditable Terraform scripts.
Here are the six key steps of an industrialized DR action plan:
- Access, Connection to the isolated DR bastion in the secondary region.
- IaC, Network and instance deployment via Terraform.
- S3, Verification of connectivity to production backups.
- Setup, Automated installation of Netweaver and HANA software.
- Restore, HANA database restoration and EFS volume mounting.
- Validation, Application consistency test and user access opening.
This method transforms a complex manual process into an orchestrated sequence. The separation between application (AWS DRS) and database is crucial. It allows using the best replication mechanism for each layer.
Field experience: Hypercare and ground reality
Optimization should not come at the expense of post-recovery stability. Hypercare phases show that performance depends on fine-tuning. During failover, EBS throughput must match production. Degraded storage can paralyze business activity during recovery. Memory peaks in "Private Mode" (PRIV) are often observed. Too short a timeout can cause work process crashes. It is recommended to gradually adjust these parameters (from 30 to 60 min). Field expertise shows that load resilience is the real challenge. A "low cost" DR must remain a credible DR, tested regularly.
What concrete gains to expect from SAP Cloud (ROI)
Moving from active DR to a hybrid model radically transforms your budget. Savings on EC2 compute is the main success factor. Client feedback often indicates a threefold reduction in DR costs. ROI also includes the reduction of human time managing tests. An automated drill via Terraform takes a few hours versus several days manually. Operational maturity is measured by the ability to avoid waste. The "Start/Stop + Pilot Light" model is today's modern SAP standard. As a CTO, you secure the business at a fair cost.
FAQ
Is the Pilot Light model certified by SAP for HANA?
SAP supports HANA backup restoration on AWS as a DR method. The recovery time (RTO) is longer than with HSR replication. However, data integrity is perfectly guaranteed by native SAP tools.
Can Start/Stop be automated without complex scripts?
AWS offers services like "AWS Systems Manager for SAP". They facilitate coordinated shutdown and startup of instances and databases. This drastically reduces the need for custom manual scripts.
How to manage failback after a disaster?
Failback is the most complex step in a recovery plan. It requires synchronizing data entered in DR back to the primary site. Using EBS snapshots and S3 replication greatly facilitates this reverse switchover.