VAXft
| Industry | Computer hardware |
|---|---|
| Predecessor | VAX |
| Founded | 1990 |
| Founder | Digital Equipment Corporation (DEC) |
| Products | Fault-tolerant minicomputers |
| Parent | Digital Equipment Corporation |
The VAXft series consisted of minicomputers designed for fault tolerance, created by Digital Equipment Corporation (DEC) and powered by processors based on the VAX instruction set architecture (ISA). The term "VAXft" represented "Virtual Address Extension, fault tolerant". These machines operated on the OpenVMS operating system, with initial support introduced in VMS version 5.4. Two essential software components, VAXft System Services and VMS Volume Shadowing, provided the mechanisms for fault tolerance and ensured data redundancy across hard disk drives.
Architecture
Every VAXft system employed a uniform design featuring two separate "zones" functioning in lock-step synchronization: designated as "Zone A" and "Zone B". Each zone was a complete, independent computer capable of running an operating system. Hardware integrated within the CPU modules maintained lock-step coordination by using crosslink cables that carried instruction outcomes between the zones for verification. A clock signal transmitted through these cables kept both zones aligned in time. When one zone experienced hardware failure, it was isolated and taken offline while the other zone continued operating without interruption. Once repairs were completed, the offline zone could be reactivated and would automatically synchronize to reestablish full redundancy.
VAXft Model 310
The VAXft Model 310, originally launched as the VAXft 3000 Model 310 under the codename "Cirrus", debuted in February 1990 with shipments commencing in June of the same year. This model marked DEC's initial broadly available fault-tolerant computer. In 1991, it was renamed to conform with updated VAXft product naming conventions. The Model 310 offered a maximum theoretical throughput of 3.8 VUPs.
At its introduction, pricing for the Model 310 began at US$200,000; however, due to sluggish market response, DEC lowered the price to US$168,000 by August 1990.
The configuration incorporated dual KA520 CPU modules—one assigned per zone—each equipped with a 16.67 MHz (60 ns cycle) CVAX+ chipset and a 32 KB external secondary cache, operating in lock-step to achieve fault tolerance.
VAXft Model 110
Announced on 18 March 1991 alongside three other variants, the VAXft Model 110, also carrying the codename "Cirrus", represented an entry-level option within the VAXft lineup. It served as a cost-effective alternative to the Model 310, capable of delivering up to 2.4 VUPs.
This model housed two zones adjacent to each other within a single chassis but offered more limited expansion capabilities regarding memory, storage, and add-on options compared to the Model 310. It was available in both pedestal and rackmount forms; the rackmount edition was designed to fit standard 19-inch RETMA racks.
Each zone was built around a five-slot backplane accommodating a KA510 CPU module, between one and three 32 MB MS520 memory modules, one or two KFE52 system I/O controllers, as well as one or two DEC WANcontroller 620 (DSF32) wide area network adapters. The minimal setup included a CPU module paired with memory and a system I/O controller.
The DEC WANcontroller 620 offered two synchronous communication lines each supporting 64 KB bandwidth; these lines could function independently or be configured together for failover protection.
VAXft Model 410
The VAXft Model 410, carrying the codename "Cirrus II", was introduced as a mid-tier model on 18 March 1991 alongside other systems. Although initially scheduled for release in June or July, its shipment was postponed until September 1991 to allow optimization of a new VMS version tailored for this platform.
While architecturally similar to the Model 310, this model utilized the KA550 CPU module featuring a faster 28.57 MHz (35 ns cycle) SOC microprocessor along with a larger external secondary cache of 128 KB. The Model 410 supported memory capacities up to 256 MB and delivered performance reaching up to 6.0 VUPs.
VAXft Model 610
The VAXft Model 610, also known by the codename "Cirrus II", was unveiled on 18 March 1991 along with several other models but experienced a shipment delay until September due to the need for VMS optimization.
This model shared its design principles with the Model 410 but arranged its two zones vertically within a 60-inch tall cabinet, specifically engineered for data center settings. The cabinet provided expanded storage capacity and accommodated one or two expander cabinets on each side for additional storage devices, all cooled by a front-to-back airflow system.
VAXft Model 612
Announced concurrently with three other models on 18 March 1991, the VAXft Model 612 represented a high-performance solution. Although initially planned for release in June or July of that year, it was postponed until September to allow fine-tuning of a new VMS version tailored to this system. The Model 612 consisted of a VAXcluster configuration combining two VAXft Model 610 units with a standard expansion cabinet positioned between them, achieving a theoretical maximum throughput of 12.0 VUPs. Additionally, another expansion cabinet could be inserted between the system units for further capacity.
VAXft Model 810
Introduced in October 1993—later than its originally anticipated late summer or early autumn 1992 launch—the VAXft Model 810, codenamed "Jetstream", was developed by DEC and produced by the Italian manufacturer Alenia SpA. This third-generation VAXft system delivered a theoretical peak performance rating of 30.0 VUPs.
The Model 810 incorporated two zones stacked vertically within a single cabinet and offered an optional expansion cabinet alongside two uninterruptible power supplies, one dedicated to each zone. It featured the KA560-AA CPU module, which housed dual 83.33 MHz (12 ns cycle) NVAX+ microprocessors equipped with 512 KB of L2 cache operating in lock-step mode. Each system contained two such CPU modules—one per zone—also synchronized in lock-step.
The dimensions of the Model 810 cabinet were 60 cm in width, 170 cm in height, and 86 cm in depth.