# Core Banking Modernization Playbook
**DigiWorkHub · IBM Power10 consolidation · v1.0 · 2026**

How we sequence consolidation of legacy AIX / IBM i workloads onto IBM Power10 in a regulated banking environment without taking the core offline.

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## Phase 0 — Discovery (Week 0–2)

- Workload inventory: every LPAR, partition, queue manager, batch window
- Dependency mapping using packet capture + AIX `topas` history
- Performance baseline: CPU, memory, IOPS, network for p95 and p99
- Compliance scope: SBV circulars, ISO 27001 controls, PCI DSS boundaries
- Stakeholder RACI signed off by CTO, CISO, Head of Operations

**Exit gate:** approved architecture, capacity plan, risk register.

## Phase 1 — Landing Zone (Week 2–4)

- Power10 hardware staged in primary + DR data centers
- HMC, PowerVM, VIOS hardened to internal baseline
- Network segmentation matching production VLANs
- Storage replication (SVC / FlashSystem) under test
- Backup target (Spectrum Protect) wired in

**Exit gate:** landing zone passes pen-test and DR drill.

## Phase 2 — Pilot Workload (Week 4–7)

- Pick a low-criticality workload (reporting LPAR, dev/test pool)
- Live partition mobility (LPM) drill
- Application team validates SLA on new platform for 14 days
- Capture lessons; update runbook

**Exit gate:** pilot meets SLA, runbook updated.

## Phase 3 — Non-core Production (Week 7–10)

- Channels (e-banking gateway, IVR backend), card management
- Cutover windows: 02:00–04:00 local, with 4-hour rollback gate
- Real-time replication kept hot until acceptance
- War-room with vendor + customer + DigiWorkHub on every cutover

**Exit gate:** 7-day stable run with no SEV-1.

## Phase 4 — Core Cutover (Week 10–12)

- Final replication catch-up < 5 minutes lag
- T-24h: regulator notified per SBV circular
- T-0: read-only mode → switchover → smoke tests
- T+2h: cautious full transactional load
- T+72h: rollback gate closed

**Exit gate:** independent QA sign-off, regulator filing complete.

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## Risk Register (Top 5)

| Risk | Likelihood | Impact | Mitigation |
|------|------------|--------|------------|
| Replication lag spikes during cutover | M | H | Pre-cutover throttle test, 2× bandwidth headroom |
| Hidden batch dependency | M | H | Two-week shadow run, business-as-usual signoff |
| Vendor patch breaks LPM | L | H | Pin firmware, vendor support engaged 24/7 |
| Regulator timing change | L | M | Filing buffer 5 working days |
| Key staff unavailable | M | M | Two-deep on every role, runbook is the source of truth |

## SLA Targets During Migration

- Channel availability: ≥ 99.95% (no degradation vs baseline)
- Transaction latency p95: ≤ baseline + 5%
- Cutover window adherence: 100%
- Zero data loss (RPO = 0 on synchronous replication)

## Rollback Gates

Every cutover has three explicit gates:
1. **T+15 min** — smoke test passes
2. **T+2 h** — full transactional load stable
3. **T+72 h** — independent QA + business signoff

Failure at any gate triggers documented rollback within the original window.

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**This is the playbook we use on every engagement.**
Adapt freely. Questions: contact@digiworkhub.com

© DigiWorkHub.