AS/400 System Savings: Why the Old Workhorse Still Wins on Cost

If you are running an AS/400 system today, chances are it is not because you are stuck in the past. It is because, quietly and without drama, it keeps doing its job. While everyone else is busy chasing rewrites, migrations, and cloud invoices that never seem to go down, the AS/400 keeps processing orders, payroll, inventory, and financials with almost boring reliability.

What often gets overlooked is this: the AS/400 is not just stable. It is cheap in ways modern platforms struggle to match. And the data backs that up: in a 2025 IBM i Marketplace Survey, a record-high 96% of respondents said IBM i delivers better ROI than other server platforms. That number has never dropped below 90% in over a decade of analysis.

What the AS/400 System Actually Is Today

Originally introduced by IBM in 1988, the AS/400 has evolved into what is now known as IBM i running on Power Systems. Under the hood, it combines:

• An integrated operating system
• A built-in relational database (Db2 for i)
• Security, backup, job scheduling, and workload management as native features

That tight integration is the secret sauce. Instead of stitching together dozens of tools, the AS/400 system ships as a single, coherent platform.

Where the Real Savings Come From

1) Lower Operational Overhead

On many modern stacks, the cost is not the server. It is the people and the tooling.

With an AS/400 system:

• No separate database licenses
• No third-party schedulers required
• No fragile backup scripts glued together over time

One or two skilled administrators can run environments that would require entire teams elsewhere. In fact,survey data shows that 77% of IBM administrators rarely or never need to reboot their servers, compared to just 52% of Dell admins and 41% of Windows admins. Result: lower headcount costs and fewer emergency outages.

2) Hardware Longevity That Borders on Ridiculous

AS/400 and Power Systems hardware is designed to run for years. Not “cloud years” but real years.

• 7 to 10 year hardware lifecycles
• Planned upgrades instead of forced migrations
• Near-zero unplanned downtime

How near zero? According to the 2024 Global Server Reliability Report, 89% of IBM Power10 enterprises achieved eight nines of uptime (99.999999%), equating to roughly 315 milliseconds of unplanned downtime per server per year. IBM Power Systems have held the top reliability ranking among mainstream server platforms for over 15 consecutive years.

Compare that with commodity x86 servers or cloud VMs that need constant tuning, resizing, and re-architecting. IBM survey 2022 found that IBM Power Systems deliver up to 60x lower total cost of ownership compared to the least efficient commodity platforms. Result: capital costs amortized over a much longer period.

3) Software Licensing That Does Not Explode

Modern platforms love usage-based pricing. Storage, compute, I/O, backups, replicas, logs. Every action has a meter running.

• Core OS and database bundled
• Predictable licensing tied to system size
• No surprise egress or API fees

For stable workloads, this predictability alone can save six figures annually. And with 98% of enterprises now reporting that a single hour of downtime costs over $150,000 (per ITIC research), the bundled approach pays for itself every time it prevents an outage that other stacks would have generated.

4) Security by Design (Not by Add-On)

Security on the AS/400 system is not an afterthought. Object-level security, user profiles, and authority management are built into the OS.

• Fewer third-party security tools
• Less audit remediation effort
• Lower compliance costs over time

In regulated industries, this translates directly into savings during audits. ITIC’s reliability surveys have consistently found that IBM Power Systems experience the fewest successful data breaches and the least security-related downtime among all mainstream server distributions tested.

Modernization Without the Rewrite Tax

One of the biggest myths is that keeping an AS/400 system means rejecting modern tools. In reality, many organizations:

• Expose RPG or COBOL logic via APIs
• Integrate with cloud analytics and AI platforms
• Archive historical data off the system to reduce storage and performance load, using solutions like Solix Enterprise Cloud Solution (ECS), an IBM-listed partner solution designed for intelligent data archiving, application retirement, and compliant data management across ERP, CRM, and legacy systems

The key is selective modernization, not wholesale replacement.

A practical governance note from the enterprise AI world: security and explainability only hold up when access controls and lifecycle rules are enforced at the data layer, not bolted on later. That theme showed up repeatedly in academic and industry discussions at UC San Diego’s Explainable and Secure Computing AI Symposium.

The True Cost of a Platform Migration

• Years of parallel system operation
• Re-training entire teams
• Business logic bugs that only surface in production
• Performance regressions under real load

A full migration is rarely just a lift-and-shift. It is a multi-year business transformation, and the hidden costs often land in testing, reconciliation, and the operational risk of re-implementing decades of proven logic. Kyndryl’s 2025 State of Mainframe Modernization Survey found that practitioners achieving the best results are biting off smaller incremental modernization projects rather than attempting a “Big Bang” replatform, and that these modernizations deliver better ROI than other IT initiatives.

When AS/400 Is Not the Best Fit

To be fair, the AS/400 (IBM i) is not the right answer for every scenario. You may lean elsewhere when:

• You need rapid elastic scaling for highly variable workloads
• You are building greenfield applications that are cloud-native by design
• Your organization lacks IBM i skills and is unwilling to invest in training or managed services
• Your UX requirements demand a full front-end modernization program

The cost advantage is strongest for stable, transaction-heavy core systems where the integrated design reduces tooling sprawl, staffing load, and compliance overhead.

Final Takeaway

The AS/400 system is not cheap because it is old. It is cheap because it was engineered correctly from the start. Integration, reliability, and predictability compound over time, and decades later, that design still pays dividends.

How much are you really saving by leaving a system that already works?

Before embarking on a costly migration, run a true 5 to 10 year TCO analysis that includes licensing, staffing, security tooling, audit effort, and risk. The numbers often show that strategic modernization beats replacement.

Disclosure: This article reflects the author’s professional perspective and operational observations. It is not official IBM guidance. Data cited from ITIC reliability surveys and Fortra’s IBM i Marketplace Survey are independent, third-party research.