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VOV Subsystem Administrator Guide
This manual provides information about managing a VOV project, including starting the server and connecting computing resources such as computers and licenses.
Recovery and Redundancy
Failover Server Candidates
If a server crashes suddenly, VOV has the capability to start a replacement server on a pre-selected host. This capability requires that the pre-selected host is configured as a failover server.

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View new features for VOV Subsystem 2025.1.0.
Overview
Discover the workspace, licensing and installation, and training.
VOV Subsystem Tutorials
Discover VOV Subsystem functionality with interactive tutorials.
VOV Subsystem Administrator Guide
This manual provides information about managing a VOV project, including starting the server and connecting computing resources such as computers and licenses.
- Client/Server Architecture
  All of Altair Accelerator's products are based on a client/server architecture to support concurrent activities, team coordination, distributed data management, and distributed processing. The program vovserver runs in the background as a service to implement the main product features. It is the server.
- VOV Projects
  A "project" is a named collection of jobs, together with all the files that are used and produced by those jobs. The contents of VOV projects can be custom organized.
- VOV Registry
  The VOV Registry contains the list of all projects known to an installation of Altair Accelerator software. The registry is used by the vovproject command, and stores metadata such as the host machine and port number of a project.
- Get Started
- Start and Configure the Server
- Connect to a Project
- Stop the Server
- Recovery and Redundancy
  - Failover Server Candidates
    If a server crashes suddenly, VOV has the capability to start a replacement server on a pre-selected host. This capability requires that the pre-selected host is configured as a failover server.
  - How vovserver Failover Works
    If the vovserver crashes, after a period of time, the vovtasker process on each machine notices that it has had no contact from the server, and it initiates a server machine election.
  - Crash Recovery Mode
    Crash Recovery Mode is activated the next time the server is restarted, if the server was not shut down cleanly. Crash Recovery Mode is part of the Failover Server capability of VOV, which is mainly used in Accelerator. This capability allows VOV to start a new server to manage the queue of a server which has crashed unexpectedly.
- Files, Equivalences, Exclusions
  The files used in a project reside in one or more directories spread all around your filesystems. Each logical name defined in the equiv.tcl file implicitly declares the root of a workspace. You can browse the workspaces using the browser interface.
- Taskers
  A tasker is a VOV client that provides computing resources, specifically CPU cycles, to the vovserver.
- Tasker Policies
- Interfaces to Accelerator, SGE, LSF, and Others
  FlowTracer can be used also as a front end to an existing batch processing system (BPS), for example, Accelerator, LSF, SGE, SGEEE, etc.
- Advanced Tasker Topics
- Resource Management
  Altair Accelerator includes a subsystem for managing computing resources. This allows the design team to factor in various constraints regarding hardware and software resources, as well as site policy constraints.
- IT Administrator Topics
VOV Subsystem Reference Guide
EDA Tool Integration Guide
This document is a collection of techniques that have proven to be useful when applying FlowTracer in Electronic Design Automation.

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Failover Server Candidates

If a server crashes suddenly, VOV has the capability to start a replacement server on a pre-selected host. This capability requires that the pre-selected host is configured as a failover server.

The configuration instructions follow.

Note: The vovserverdir command only works from a VOV-enabled shell when the project server is running.

Edit or create the file servercandidates.tcl in the server configuration directory. Use the vovserverdir command with the -p option to find the pathname to this file.
```
% vovserverdir -p servercandidates.tcl
/home/john/vov/myProject.swd/servercandidates.tcl
```
The servercandidates.tcl file should set the Tcl variable ServerCandidates to a list of possible failover hosts. This list may include the original host on which the server was started.
```
set ServerCandidates {
    host1
    host2
    host3
}
```

Install the autostart/failover.sh script as follows:

% cd `vovserverdir -p .`
% mkdir autostart
% cp $VOVDIR/etc/autostart/failover.sh autostart/failover.sh
% chmod a+x autostart/failover.sh

Activate the failover facility by running vovautostart.
```
% vovautostart
```
For example:
```
% vovtaskermgr show -taskergroups
ID         taskername        hostname         taskergroup
000404374  localhost-2      titanus          g1
000404375  localhost-1      titanus          g1
000404376  localhost-5      titanus          g1
000404377  localhost-3      titanus          g1
000404378  localhost-4      titanus          g1
000404391  failover         titanus          failover
```
Note: Each machine listed as a server candidate must be a vovtasker machine; the vovtasker running on that machine acts as its agent in selecting a new server host. Taskers can be configured as dedicated failover candidates that are not allowed to run jobs by using the -failover option in the taskers definition.

Preventing jobs from running on the candidate machine eliminates the risks of machine stability being affected by demanding jobs. The -failover option also enables some failover configuration validation checks. Finally, failover taskers are started before the regular queue taskers, which helps ensure a failover tasker is available as soon as possible for future failover events.

Refer to the tasker definition documentation for details on the -failover option.