IBM Power Disaster Recovery: Options and Planning
How should you plan disaster recovery for IBM i, AIX, and Power workloads?
Start by defining RPO (Recovery Point Objective) and RTO (Recovery Time Objective) targets by workload, then choose a DR approach — backup-and-restore, replicated standby, or hosted DRaaS — that can actually meet those targets at a cost profile you can sustain, and test it on a regular cadence. Most DR gaps come not from choosing the wrong technology but from never testing the plan or letting it drift out of date.
At a glance
Key takeaways
RPO/RTO should come from the business, not IT
Recovery targets should reflect what the business can actually tolerate, not what's technically convenient to build.
An untested plan is not a plan
DR architecture that has never been through a real failover test carries hidden risk regardless of how it was designed.
Regulatory requirements can set a floor on RPO
Some industries and data types carry compliance-driven recovery requirements that should be confirmed, not assumed.
Cost scales with how close to zero you need to get
Near-zero recovery targets require the most expensive architectures — match ambition to actual need.
Define RPO and RTO by Workload
RPO (Recovery Point Objective) is the maximum acceptable amount of data loss, measured as a point in time. RTO (Recovery Time Objective) is the maximum acceptable time to restore service after an outage. These should be defined per workload or application, not as a single blanket target for the whole environment — a core ERP system and a low-priority reporting server usually warrant very different recovery targets.
Involve business stakeholders directly in setting these targets, since RPO/RTO decisions are fundamentally about acceptable business impact, not a purely technical calculation IT can make in isolation.
Replication Approaches
Backup-and-restore — BRMS-based saves or mksysb images shipped to offsite or cloud storage and restored on demand — is the lowest-cost approach but carries the longest RTO. Remote journaling or logical replication continuously (or near-continuously) replicates database changes to a standby system, offering moderate cost with RPO measured in seconds to minutes.
Storage-based replication, whether synchronous or asynchronous, replicates data at the storage layer and is often paired with PowerHA to orchestrate automated failover once replication is in place. This is the highest-cost approach but can achieve very low RPO and RTO when configured and tested correctly.
Hosted and DRaaS Options
DRaaS (Disaster Recovery as a Service) is a vendor-hosted, subscription-based DR environment that removes the need to own and maintain standby infrastructure. Offerings typically span a spectrum from cold (infrastructure provisioned only after a disaster is declared, lowest ongoing cost, longest RTO) to warm (standby infrastructure exists but isn’t continuously running production, moderate cost and RTO) to hot (fully replicated and ready to fail over quickly, highest cost, lowest RTO).
DRaaS is particularly attractive for organizations that don’t want the capital cost and operational burden of owning and maintaining a second physical site.
Testing Cadence
As an illustrative cadence only, many organizations run a full failover test annually, supplemented by more frequent tabletop or partial tests — though the right frequency should reflect your regulatory requirements and risk tolerance. A tabletop exercise walks through the runbook without executing it; a partial test fails over a subset of systems; a full failover test actually runs production from the DR environment for a defined period.
Many organizations only discover gaps in their DR plan during a real event, because testing was skipped entirely or kept superficial. Regular, honest testing is what turns a DR design on paper into a plan that actually works.
Common Gaps: Untested Plans, Aging Runbooks, and Insufficient RPO
Recurring failure patterns include DR runbooks that still reference retired staff, decommissioned systems, or outdated network diagrams; replication that was configured correctly once but has silently fallen behind or failed without triggering an alert; and RPO targets that were adequate when first set but no longer meet current regulatory or business requirements as the organization has grown or entered new regulatory regimes.
Treat the DR plan as a living document, reviewed at least annually and after any significant infrastructure, staffing, or regulatory change — not a document written once and filed away.
Matching DR Approach to Requirements
Match workload criticality to DR investment. Mission-critical systems with near-zero tolerance for data loss or downtime justify replicated or hot DRaaS approaches. Lower-priority systems may be well served by a simpler backup-and-restore approach.
Over-engineering DR for low-priority systems is a real and avoidable cost — the goal is to match the approach to the actual RPO/RTO requirement for each workload, not to apply the most robust option everywhere by default.
DR Approach, RPO/RTO Fit, and Cost Profile
Use this table to match a DR approach to your recovery targets and budget.
| Option | Typical RPO/RTO fit | Cost profile |
|---|---|---|
| Backup and restore (BRMS/mksysb to offsite storage) | RPO: hours to a day; RTO: hours to days | Lowest — pay mainly for backup storage and occasional restore testing |
| Remote journaling / logical replication | RPO: seconds to minutes; RTO: tens of minutes to hours | Moderate — standby compute/storage plus replication licensing |
| Storage replication + PowerHA automated failover | RPO: near-zero to seconds; RTO: minutes | Higher — fully provisioned standby environment kept continuously in sync |
| Cold DRaaS | RPO: hours; RTO: a day or more | Low ongoing cost, higher cost and time at the point of use |
| Warm DRaaS | RPO: minutes to hours; RTO: hours | Moderate — partial standby capacity reserved continuously |
| Hot DRaaS / active-standby | RPO: near-zero; RTO: minutes | Highest — fully replicated, ready-to-fail-over environment maintained continuously |
Implementation Steps
- 1
Classify workloads by criticality
Group applications into tiers as the basis for setting different RPO/RTO targets.
- 2
Set RPO/RTO with business stakeholders
Confirm acceptable data loss and downtime windows per tier, including any regulatory floors.
- 3
Select a DR approach per tier
Match backup-and-restore, replication, or DRaaS options to each tier's targets and budget.
- 4
Build and document the runbook
Capture failover/failback procedures, contacts, and dependencies in a runbook kept current.
- 5
Test on a defined cadence
Run tabletop, partial, and full failover tests on a schedule matched to risk tolerance and compliance needs.
- 6
Review after every major change
Re-validate the plan whenever infrastructure, staffing, or regulatory requirements change materially.
Risks and Common Mistakes
Use caution
Never fully testing failover
A DR architecture that looks correct on paper but has never been through a real failover test carries hidden, unquantified risk.
Use caution
Letting runbooks and contacts go stale
Runbooks that reference retired staff, decommissioned systems, or outdated diagrams can turn a real event into a much longer outage than planned.
Use caution
Setting RPO/RTO without checking regulatory requirements
Some industries and data types carry compliance-driven minimum recovery requirements — confirm these before finalizing targets, not after an audit.
Frequently Asked Questions
What is the difference between RPO and RTO?
RPO (Recovery Point Objective) is how much data loss is acceptable, measured as a point in time. RTO (Recovery Time Objective) is how much downtime is acceptable before service must be restored. They're usually set together but represent different dimensions of business impact.
How often should I test my DR plan?
At minimum annually for a full failover test, with more frequent tabletop or partial tests in between — though the right cadence depends on your regulatory requirements and risk tolerance. The key is testing regularly enough that the plan reflects current infrastructure and staffing.
What is DRaaS?
Disaster Recovery as a Service is a vendor-hosted, subscription-based DR environment, ranging from cold (infrastructure provisioned only after a declared disaster) to hot (continuously replicated and ready to fail over quickly).
Do I need PowerHA for disaster recovery?
Not necessarily. PowerHA is commonly used to orchestrate automated failover once replication is in place, but backup-and-restore or manual failover approaches may be sufficient for workloads with more relaxed RPO/RTO targets.
Why do DR plans fail during a real event even when the technology is sound?
Most real-world DR failures come from untested procedures, outdated runbooks, or replication that silently drifted out of sync — not from the underlying replication technology itself.
Sources
- IBM PowerHA and replication documentation
- Industry disaster recovery and business continuity frameworks
- Vendor DRaaS service guides
Not Sure Your DR Plan Would Hold Up?
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