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Re-Hosting SPARC, Alpha, or Other Legacy Systems to AWS with Stromasys

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By Thomas Netherland, Global Head of Alliances at Stromasys

Companies still rely on mission-critical applications running on Sun SPARC, Alpha, or other legacy systems like PDP, VAX, or HP 3000. As time goes on, however, the maintenance costs for these systems goes up, and reliability declines due to their age.

Re-architecting these applications is complex and expensive. Fortunately, they can be re-hosted on Amazon Web Services (AWS) in a matter of days using cross-platform hypervisors from Stromasys, an AWS Partner Network (APN) Standard Technology Partner.

In this post, we’ll describe the challenges customers face with legacy systems, the Stromasys technical solution, and a successful customer migration to AWS.

Legacy Systems Customer Challenges

Legacy systems survive because they address a business need. However, mission-critical legacy applications and their respective operating systems are subject to a version of hardware model and exclusive vendor that has already reached the end of its existence.

Most often, the life of the hardware is shorter than that of the software. Over the years, the hardware becomes more difficult to maintain but is retained because it’s installed and working for the moment.

Legacy systems are often too complex or expensive to replace. However, system performance tends to decline over time due to increased frequency of hardware failure and low reliability of reconditioned spare parts. Thus, legacy system availability costs continue to rise.

There are millions of legacy systems across all industries executing business-critical workloads—banks, energy companies including nuclear plants, manufacturing and process control, defense, transportation, hospitals, government, education, insurance, and more.

End-of-Life Hardware Remediation

The applications themselves are operational: they work, they execute their business function, and they don’t need to be replaced. Sometimes they cannot be replaced. It’s mostly the hardware, not the software, that presents a business risk and added expense. Relying on the supply of spare parts for the replacement of faulty components is both unreliable and a short-term solution.

Hardware emulation is a quick and cost-effective solution to extend the application’s useful life. Emulation, also called cross-platform virtualization, reproduces the legacy hardware behavior in a healthy manner by avoiding physical pitfalls and expensive repairs. It preserves the application’s functionality and operating environment. It also adds flexibility with cloud benefits, such as capacity changes in minutes and a pay-as-you-go model.

Stromasys Emulators

Charon is the brand name of a family of legacy system emulators from Stromasys. Charon software emulates legacy hardware such as SPARC, VAX, Alpha, PDP, or HP 3000. Each emulator creates a virtual legacy environment on a standard Windows- or Linux-based host system, with or without VMware ESXi hypervisor configurations.

Figure 1 shows how the legacy system hardware is replaced with Stromasys Charon emulator.


Figure 1 – Legacy hardware replaced by Stromasys Charon emulator.

Charon creates accurate hardware models of emulated systems in software for the Intel X86_64 platform, including all type of peripherals used on each different architecture.

This way, the legacy systems are replaced by a hardware abstraction layer on new industry standard servers based on Intel X86_64 architecture, while the original complete operating system and user application can continue to run unmodified in an identical environment as the one provided by the legacy system replaced. It preserves user interfaces and protocols.

Charon can be classified as a Hypervisor II that provides cross platform binary compatibility for different architectures.

Migration from legacy systems can be done using existing backups, or by creating and transferring them via network or any storage device to Charon. Fresh installation of legacy operating system and applications can also be done on Charon as in the original systems to be replaced.

The following list show some of the Stromasys emulators and the legacy platforms they emulate:

  • Product: Charon PDP
    Hardware Virtualized: PDP-11/93 for Qbus systems, PDP-11/94 for Unibus systems
    Operating Systems: RSX-11, RSTS, RT-11
  • Product: Charon VAX
    Hardware Virtualized: MicroVAX II, VAX 3600/3900, VAX 4000/100, VAX 400/106, VAXStation 4000/90, VAX 6610 – 6660
    Operating System: OpenVMS
  • Product: Charon AXP
    Hardware Virtualized: Alphaserver DS,ES,GS series, Alphaserver 400,800,1000,1200,2000,2100,4000,4100
    Operating Systems: OpenVMS, Tru64 UNIX
  • Product: Charon SSP
    Hardware Virtualized: SPARC SUN4M and SUN4U families
    Operating Systems: SunOS , Solaris
  • Product: Charon HPA
    Hardware Virtualized: HP3000 families
    Operating Systems: MPE

Emulators on AWS

Stromasys emulators can be deployed on Amazon Elastic Compute Cloud (Amazon EC2) or VMware Cloud on AWS. Virtual SPARC for VMware Cloud on AWS is available here, while Virtual Alpha for VMware Cloud on AWS is available here.

Figure 2 shows a legacy application and Charon deployment on Amazon EC2 instances.


Figure 2 – Stromasys Charon emulator on AWS.

The Charon emulator is installed on top of a Linux operating system running within an Amazon EC2 instance. The legacy application is restored on top of the Charon emulator within the Amazon EC2 instance, including the legacy operating system, any legacy middleware, and any legacy database necessary for the legacy application. Based on the application topology and availability requirements, it can be deployed across two or more Availability Zones (AZs).

Corporate users now access their legacy application via a secure connection with a Virtual Private Network (VPN) and/or AWS Direct Connect. Users can directly access the legacy operating system IP, or in some cases a bridge is used.

Legacy applications on Charon on AWS benefit from the AWS CPU fast-clock speeds. The newly-announced high frequency z1d instances deliver a sustained all core frequency of up to 4.0 GHz, the fastest of any cloud instance.

Amazon EC2 Bare Metal instances also accommodate the installation of Charon Barebone, which is a software offering combining both the Charon emulator along with the underlying Linux operating system and delivered as custom images.

Performance, Availability, Scalability, Disaster Recovery

From a performance perspective, customers are often surprised. When virtualizing old hardware that has been around for 20 or 30 years on modern x86 infrastructure, the newly-available CPU clock-speeds more than compensate for the real-time emulator instructions translation overhead.

By removing the old hardware and its high risk of failure, and moving to AWS with recent hardware, the inherent availability of the application stack is improved. Furthermore, if the application is deployed across multiple instances, these instances can be spread across AZs for higher availability.

Most legacy systems workloads are stable in use and don’t require capacity changes. Nonetheless, if the legacy application demand changes, and more or less resources are needed, AWS instances allow vertical scalability (changing instance type for larger or smaller resources) or horizontal scalability (changing the number of parallel instances). Such change can be done in a matter of minutes following a pay-as-you-go model.

Disaster recovery on legacy systems is usually handled by backup tapes, or clusters. Once moved to Charon emulation on AWS, legacy applications and data can benefit from the same best practices as for other AWS workloads including Amazon Simple Storage Service (Amazon S3) or Amazon Glacier backup and restore, Pilot Light, Warm Standby, Multi-Region.

Migration to AWS Process

For migrating a legacy system to AWS, Charon emulator is first preloaded into the AWS instance and waits to receive the legacy application and the legacy operating system. Then, a backup of the legacy system is taken, transferred to AWS, and restored onto the Charon emulator. This process typically completes in a matter of days.

One option is to transfer the legacy system backup archive over a secure network. For large data uploads or tight go-to-live schedules, the AWS Snowball data transport solution can be beneficial. Figure 3 shows the migration process.


Figure 3 – Migration to AWS process.

The steps to migrate a legacy system to AWS include:

  1. Launch an Amazon EC2 instance with Amazon Elastic Block Store (Amazon EBS) volumes similar in size to those on the original legacy system.
  2. Set up network connectivity between the original legacy system and the new Amazon EC2 instance, or prepare an AWS Snowball job.
  3. Backup the original legacy system creating a backup archive.
  4. Transfer the backup archive to the new Amazon EC2 instance either over the secure TCP/IP network, or via AWS Snowball.
  5. Restore the legacy system onto the Charon emulator within the Amazon EC2 instance.
  6. Start the emulated legacy system on Amazon EC2 instance.
  7. Adjust and verify network configuration.
  8. Cleanup unused legacy files, if any, such as hardware databases.

Depending on the legacy system, Stromasys can provide tools to semi-automate the migration process accelerating backup and restore activities.

Stromasys Use Case on AWS

One of the world’s largest mining companies had to modernize a critical legacy application running on past-end-of-life DEC Alpha hardware running Tru64 UNIX. The legacy financial application stores and retrieves historical records in an Oracle database, and is critical for compliance purposes.

Repairing the legacy hardware with the help of user groups was not a viable long-term solution. Legacy system failure leading to missed SLAs and non-compliance was just too expensive, and yet too close to a reality. Something needed to be done quickly about this high-risk situation.

The customer took full advantage of Charon-AXP’s DEC Alpha system virtualization to move the legacy application to AWS cloud, with no change to the application or operating system. The project was completed within two weeks.

Legacy equipment replaced:

  • Application server: Alpha DS25 2-cpu (1000 MHz), 4 GB RAM, 188 GB storage.
  • Database server: Alpha GS80 8-cpu (1250 MHz), 16 GB RAM, 4 TB storage.

Target Amazon EC2 instances:

  • Application server: c4.2xlarge instance with 8-cpu (2.9 GHz), 15 GB RAM, 300 GB storage
  • Database server: c4.4xlarge instance with 16-cpu (2.9 GHz), 30 GB RAM, 4 TB storage

Two Elastic IPs were provisioned (one for Linux operating system, and one for Tru64 UNIX operating system) and used AWS Direct Connect for network connectivity. Charon-AXP for Linux was configured to receive the legacy operating system and application.

One lesson learned from this experience is that we could have moved the data through Snowball for faster transfer instead of moving the data over network connections. This migration to Charon-AXP on AWS minimized the risks while maintaining the same end-user experience at a lower total cost.

Customer Benefits

Once the application is migrated from the legacy hardware to AWS, it not only gets a new lease on life, but options and new capabilities suddenly become available. The benefits of cross-platform virtualization with Charon on AWS include:

  • Risks of a legacy system catastrophic hardware failure are mitigated.
  • Costs are optimized moving to an AWS pay-as-you-go consumption model.
  • Application hardware capacity becomes flexible with possible adjustments in minutes.
  • AWS CPU fast-clock speeds deliver enhanced performance for applications.
  • Enterprises or organizations can now include legacy systems in their AWS mass migration plans.
  • The application is moved unchanged to AWS transparently to end-users avoiding re-certification and re-training.
  • New AWS high availability schemes and disaster recovery best practices become available to the application, and enhance the customers experience.
  • AWS automation accelerates operations and allows starting or stopping legacy environments in minutes possibly within a CI/CD pipeline.

Stromasys Support

Stromasys offers product support for Charon on AWS during business hours or 24×7 for all emulators worldwide. Support typically applies to the Charon emulator software itself. Stromasys can also offer operating system support such as support for OpenVMS 7.3 and earlier.

Implementation assistance is available at a flat rate. It is usually delivered in a matter of days. It includes assistance for the sizing of Charon solution, migration design and delivery. Other professional services are available on a scoped project basis with a Statement of Work.

Charon emulators from Stromasys eliminate the need for risky application refactoring or rewriting projects. They allow legacy systems to enjoy many AWS benefits including cost-optimization, flexibility and automation. With a simple backup/restore and no application change, end users won’t even notice the legacy platform has been moved to AWS.

The content and opinions in this blog are those of the third party author and AWS is not responsible for the content or accuracy of this post.


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Stromasys is an APN Select Technology Partner. They address customers’ data center modernization needs by allowing the movement of legacy system applications and data to x86 infrastructure, without changing any legacy code or data.

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