vtVAX Product Highlights

Operating System

vtVAX supports VAX/VMS V4.3 through OpenVMS V7.3, just like the hardware VAX.


vtVAX can be configured as VAX-cluster or OpenVMS Cluster member using Ethernet (NI) or emulated DSSI ("shared disk") interconnects. The Maintenance Operations Protocol (MOP) is supported for maintenance operations and remote booting.


vtVAX can emulate any of the following VAX systems:

  • VAX: 4000-90, 4000-100, 4000-105A, 4000-200, 7000 models 610-640 (models 650 and 660 on Bare Metal only)
  • VAXserver: 3600, 3900
  • MicroVAX: II, 3100-90, 3100-95, 3600, 3900
  • VAXstation: II, 3600, 3900

Virtualized systems can be configured with up to 512 MB of memory, subject to the configuration limits of the VAX hardware model. Some emulated models may allow for more memory than the original VAX system. vtVAX 7000 on Bare Metal may be configured with up to 3.5 GB memory.

The virtual VAX model determines the type of storage, network, and serial devices that can be used in the virtual environment.

The performance of the virtual VAX system is determined by the the host system and the workload of the emulated systems running on the host. The VAX system model is not a factor for performance.

The models listed above were chosen for emulation because they can replace systems with a wide range of VMS operating system versions, license types and device configurations. Your vtVAX reseller can assist you with the system inventory that will help to determine which vtVAX solution best meets your requirements.


Your existing software license PAKs work in the virtual VAX in the same way as when running on a physical VAX.


vtVAX has the capability to configure virtual disks, CD-ROM drives and tape devices. The virtual devices may be mapped to storage devices or container files on the host system. These container files may be located on any type of storage attached to the host: SCSI, SATA, SAS, USB, solid state, CD/DVD; iSCSI, NAS, NFS or SAN.

Emulated Qbus based systems allow for the configuration of four virtual MSCP disk controllers, each supporting 32 drives (DI, DK, and DU devices). SCSI bus systems support the configuration of two virtual SCSI controllers, each supporting eight disk devices. One virtual tape controller may be configured with up to 16 tape drives. vtVAX 7000 systems may be configured with up to eight DSSI controllers.

For reasons of performance and reliability, we recommend using VAX storage media only for the initial system setup or the retrieval of archived data. The X86 host's modern disk drives have much higher reliability, performance and data capacity. They also have less accumulated wear, are cheaper initially, and are much less expensive to operate and maintain.

Multiple container files may be stored on a single PC drive, providing for storage consolidation without changing the OpenVMS file system. VAX tape operations using logical tape drives and transfer data at disk speeds without the physical media errors commonly experienced with tape storage.


vtVAX supports virtual DELQA, DEQNA, SGEC or DEMNA Ethernet interfaces, depending on the processor model being emulated. A maximum of two DELQA/DEQNA adapters or one SGEC adapter may be configured (all three may be configured when emulating a vtVAX 4000 system). vtVAX 7000 systems may be configured with up to four virtual DEMNA adapters. Each virtual Ethernet adapter is mapped to a dedicated physical Ethernet interface on the host system. On the Bare Metal platform, a virtual switch may be used to allow multiple virtual adapters to share a single physical interface.

Network interfaces are not limited by the 10 Mbps, half-duplex limitations of a physical VAX system. The physical interfaces can be configured in any mode supported by host computer, usually 1 or 10 GBPS. In most cases this allows the virtual VAX system to achieve much higher network throughput than the VAX it replaces.

Serial lines

vtVAX emulates the DHQ11, DHV11, CXA16, CXB16, and CXY08 serial interfaces; up to a maximum of 32 ports. Each configured serial port requires a dedicated connection on the host: a serial COM port (on-board or PCI serial interface) or a Telnet connection. Telnet connections are presented as virtual devices. You only need to configure those virtual ports actually being used (i.e., if you are emulating a DHV11 and only require two of the eight ports, only two physical ports are required).


When emulating a Qbus based system, a single virtual VCB02 graphics controller can be configured, allowing the host monitor to be used as the display device for the virtual VAX.