XDelta - Mission critical systems and infrastructure
OpenVMS migration - hic sunt dracones

Migration and transition

Bespoke applications are the life blood of most organisations, often representing significant investment. Your new systems have to integrate with new infrastructure and will behave differently. The successful migration will support your business now and for future growth.

Most OpenVMS systems have the applications and operational processes tightly integrated with the operating system, hardware platform and surrounding infrastructure. These are time consuming and difficult to understand. They will be inherently difficult to migrate.

Those running large and complex systems with both high performance and high availability requirements have the greatest problem. In many cases the transition process itself is one of the major constraints on the migration design, especially with very high availability multi-site clustered systems with extensive storage and network infrastructures.

The transition problem is more one of complexity than scale. Most migrations will be relatively straightforward. Some will be exceedingly difficult. A highly complex and tightly integrated system with exceedingly demanding availability requirements and little (if any) scope for downtime will be one of the most difficult kinds of system to migrate successfully.

Here be dragons - "Hic sunt dracones"

From the earliest times, map makers used to depict scary monsters and other mythical creatures as inhabiting unknown territory. The Hunt-Lenox Globe in the New York Public Library carries the Latin inscription "Hic sunt dracones" (here be dragons). The phrase has become synonymous with entering diffioult and unknown territory. Leaders who knew how to cope with such territory were highly respected and sought after, because they greatly improved the chances of coming back alive and intact.

The scale of the migration problem:

A number of factors contribute to the overall complexity and dificulty of any systems migration project:

High performance systems:

These typically have severe constraints on throughput and responsiveness. Consistent and sustained high IO write rates to storage are particularly difficult to achieve.

High availability and multi-site systems:

These typically have severe constraints on permissible outage times. Multi-site operation brings additional complexity with long-distance data replication and the associated latency and distributed locking effects.