Most IT leaders still treat AS400 recovery like it is the early 2000s. Long backup windows, tape restores, weekend outages, and a sense that this is simply how IBM i behaves.
The platform evolved. Storage evolved. Business continuity expectations have definitely evolved. If your recovery plan still depends on tape or multi-hour restores, you do not have a recovery plan. You have a downtime plan. High Availability built on SAN architecture with reliable hourly snapshots redefines recovery from hours to minutes.
The bridge here is simple. IBM i is still the most resilient midmarket platform, but the way we protect it has not kept pace with modern risk. The gap between what the business needs and what tape-based recovery delivers has become impossible to ignore.
The Old Recovery Model Creates Hours of Exposure
For decades, shops lived with nightly tape backups, multi-hour system saves, long restore times, hardware dependencies, and manual failover steps. That model only worked when downtime was tolerable.
Today, it is not tolerable in healthcare, manufacturing, logistics, or service industries that run around the clock. A hospital we supported used to require 17 to 20 hours for a full backup. A restoration would have taken more than a day. That is not a recovery path. It is a business interruption.
The Modern Model: SAN Snapshots With Real-Time Replication
High Availability in 2025 centers on SAN-based architecture rather than internal IBM i disk. The model uses SSD arrays, doubled storage capacity, hourly snapshots, controlled LUN mapping, offsite replication, and a preconfigured standby LPAR.
The result is fast recovery, predictable data protection, and low operational risk. Recovery time drops to minutes. Data loss drops to less than an hour. It is a recovery posture aligned with how your business actually runs.
How Snapshot-Based HA Works in Practice
Here is what happens behind the scenes. Production writes land on the primary SAN. Hourly snapshots capture changed data with almost no performance impact and minimal overhead. Those snapshots replicate to a secondary SAN through encrypted links. A standby LPAR sits ready to take over without interfering with production.
In a failure event, the secondary LPAR mounts the replicated LUNs and resumes service within minutes. Most shops accept an RPO between zero and sixty minutes as the ideal balance of protection and cost.
Why SAN Snapshots Outperform Tape-Based Recovery
Tape introduces five weak points.
- Restores take too long.
- Data is always behind.
- Tape media degrades.
- Tapes do not create true DR readiness.
- Worst of all, you cannot test tape recovery the way you can test snapshot-based HA.
A SAN-based DR test takes minutes and can be executed routinely. Tape restores are disruptive and often avoided entirely. When you compare models, it stops being a technical debate and becomes a business uptime decision.
Why Leaders Delay HA Even When They Should Not
There are three recurring reasons leaders delay HA investments.
- They assume it is expensive.
- They believe their current backups are good enough.
- They underestimate the fragility of modern supply chains.
Storage failures, power events, or human errors now create cascading downtime that impacts revenue and service levels in real time. The shift toward SAN-based High Availability is accelerating because the consequences of downtime are too immediate to ignore.
What a Real Recovery Test Looks Like
I still remember one of the first full DR tests I oversaw after moving a client from tape to a SAN-based HA solution. Before the migration, their annual tape restore test took nearly an entire weekend.
Teams slept on conference room floors. Managers paced the hallways waiting for operators to confirm each completed step. Staff quietly admitted they hoped they would never have to run a real restore.
When we introduced SAN snapshot HA, the team expected similar chaos. Instead, we had the test completed before their coffee cooled. The standby LPAR mounted replicated LUNs in minutes.
Application owners logged in and verified that the data currency matched the previous hour. Compliance reviewed the evidence and asked if this speed was repeatable. It was. We ran the test again. Same result. In that moment, the leadership team understood that HA was not just a technical upgrade. It was an operational reset.
The Business Case: Minutes Versus Days
For CIOs, CFOs, and operations leaders, the difference is straightforward. SAN snapshot HA delivers minute-level RTO, sub-hour RPO, and low risk through automated failover workflows. Tape-based recovery delivers multi-hour or multi-day RTOs, day-long RPO exposure, and high operational risk.
You do not choose HA because systems might fail. You choose it because the business cannot tolerate downtime when systems fail. That is a clear business justification, not just a technical one.
Your Questions Answered
How often should IBM i snapshots run in a SAN-based HA model?
Most environments run hourly snapshots, which creates an RPO of less than sixty minutes. Some organizations use tighter intervals, but hourly is typically the best balance of load, protection level, and operational predictability.
Does SAN-based HA replace traditional tape backups entirely?
Tape can still serve as long-term archival storage, but it should not be considered a recovery mechanism. SAN snapshots handle operational recovery while tape supports retention policies. This separation of roles reduces risk and ensures that recovery timelines remain predictable.
How difficult is it to test a SAN-based HA system?
Testing is straightforward. A standby LPAR can be activated and pointed at replicated LUNs without disrupting production. Most tests only take minutes. This simplicity allows organizations to run DR exercises multiple times a year and maintain documented evidence for compliance.
Is snapshot-based HA dependent on specific IBM i versions?
Snapshot techniques operate at the storage layer, not the OS layer. As long as the SAN and replication architecture are configured correctly, most IBM i environments can benefit.
How does this model affect maintenance windows?
Snapshot HA reduces the need for long maintenance windows. Because a standby system can mount updated LUNs rapidly, maintenance tasks that once required hours of downtime now result in minimal disruption. The business gains scheduling flexibility and fewer service gaps.
What role does offsite replication play in recovery?
Offsite replication protects snapshot data from local failures such as power events or hardware faults. It forms the backbone of Disaster Recovery alignment by placing restorable copies in a secondary facility. That provides a second layer of protection beyond standard HA coverage.
Reduce Downtime Risk by Modernizing Your Recovery Plan
Real continuity comes from fast recovery and frequent testing. SAN snapshot High Availability provides leaders with predictable uptime and recovery timelines that align with the modern demands of their organizations.
If you want predictable uptime and a recovery model built for today, we can help you design and validate it. Contact our team to start a conversation.
