Documentation

Server Configuration

User Parameters

The Gurobi compute server provides a number of user-configurable parameters that can be set through a grb_cs.cnf file.

As noted in the Quick Start Guide, you start a compute server by running the grb_cs program on the server machine. This starts a Windows service on Windows systems, and a daemon on Linux or Mac OS systems. When a compute server starts, the first thing it does is to look for file grb_cs.cnf in the same directory as the grb_cs executable. You can place a list of parameter=value lines in this file to change compute server parameters. Lines that begin with the # symbol are treated as comments and are ignored. Here's an example configuration file:

# Configuration file
JOBLIMIT=2
PASSWORD=abcd1234
ADMINPASSWORD=1234abcd

You should create this file using your favorite text editor (Notepad is a good choice on Windows).

Available configuration parameters are:

JOBLIMIT

A limit on the number of client jobs that are allowed to run on the server at the same time. Client requests beyond this limit are queued. The default limit is 2.

HARDJOBLIMIT

A hard limit on the number of simultaneous client jobs. Priority 100 jobs are allowed to ignore the JOBLIMIT, but they aren't allowed to ignore this limit. Client requests beyond this limit are queued. The default hard limit is 100.

THREADLIMIT

A limit on the number of threads a client job can use. By default, a client program is allowed to create one thread for each core in the server machine.

IGNOREPRIORITIES

When set to 1, the server ignores user job priorities.

PASSWORD

The password that the client program must supply in order to submit a job. Note that all user data is passed between the client and server using 256-bit AES encryption, whether you supply a password or not. The server password simply prevents unauthorized clients from submitting jobs to the server. The default is no password.

ADMINPASSWORD

The password for performing client-server administrative tasks. This is different from the password that client programs must provide. Administrative tasks are performed using the gurobi_cl program. Example tasks include changing the job limit and killing jobs (details will follow). Note that the administrator password must be set if you wish to enable remote administration.

The configuration file is only read once, when the compute server first starts. Subsequent changes to the file won't affect parameter values on a running server.

Firewalls

A Gurobi compute server communicates with clients through a number of network ports on the server machine. By default, it uses ports 61000-65000. Most machines will either silently allow the Gurobi compute server to use these ports, or they will ask you to confirm that the Gurobi compute server can use these ports. However, some situations will require you to manually open these ports.

One notable example is Amazon EC2, where most network ports are closed by default. You'll need to create an EC2 Security Group (or modify your default group) when you start your instance in order to open these ports.

If for some reason our default port range is unavailable on your server, you can include a PORT= statement in both the client and the server license files to choose a different range. For example, the line:

PORT=43000

would use ports 43000-47000 instead.

If you run into trouble with firewall issues, we suggest you share this section with your network administrator.