MATLAB: Do redundant servers fail to run properly if the primary server is killed

MATLAB

All three redundant server can be started and a client can checkout MATLAB without any problems but when the primary server is killed no clients can checkout a MATLAB license. When the primary server is killed, the license server status indicates that the other two servers are both not running.

 -----------------
 Server Status
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 Flexible License Manager status on Mon 9/13/2004 15:25
 [Detecting lmgrd processes...]
 License server status: 27000@hsiaow,27000@namj,27000@carvalhom
     License file(s) on hsiaow: D:\MATLAB7\flexlm\license.dat:
 lmgrd is not running: Cannot connect to license server
The server (lmgrd) has not been started yet, or
the wrong port@host or license file is being used, or the
port or hostname in the license file has been changed.
 Server name:   hsiaow
 License path:  27000@hsiaow,27000@namj,27000@carvalhom
 FLEXlm error:  -15,570.  System Error: 10035 "WinSock: Operation would block"
 For further information, refer to the FLEXlm End User Manual,
 available at "www.macrovision.com".

Best Answer

This issue can occur if the MATLAB client points to the license servers via a license file instead of using the MLM_LICENSE_FILE variable. After the installation is complete the client license file should be removed and an environment variable used in its place. The client license file for MATLAB will be one or more of the following:

For R2008a and higher:

$MATLAB\licenses\network.lic

For pre-R2008a:

On Windows the client license.dat file is located in $MATLAB/bin/win32.

On UNIX/Linux/Mac this license.dat file is placed in $MATLAB/etc.

(where $MATLAB is the installation folder for MATLAB)

The environment variable that should be added is as follows:

MLM_LICENSE_FILE=port@server1,port@server2,port@server3

-port refers to the number at the end of the SERVER line in the license file. By default this is 27000.

-server refers to the hostname of your server as defined in the SERVER line of the license file.

NOTE: The entries in the environment variable must be separated by commas (","), not semicolons (";") or colons (":").

This step allows client redundancy so that if a server fails while a client license is checked out the client will search to the next server instead of posting an error. This also will remove the need to update the client license files if the server license files are changed.

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MATLAB: What are the differences between the license.lic, license.dat, network.lic, and license_info.xml license files

There are four different types of license file:

license.lic

For Individual or Designated Computer licenses, this is a standard license file generated from the MathWorks License Center. If this license is automatically generated during installation, it will also contain the hostname, license number and release in the filename.
For Concurrent or Network Named User licenses, this is an unprocessed license file used to install the network license manager. It is also generated on the MathWorks License Center. On network licenses, the license.lic file is *only *used for the installation of the network license manager.

license_info.xml

The license_info.xml file is used for Individual licenses with Login Named User enabled.
This type of license file is common for trial licenses and licenses being used on cloud compute services.
The license_info.xml file contains no license data; rather it instructs MATLAB to connect to MathWorks on launch to authenticate the license.
If a license_info.xml file is in place, you will be prompted to enter your MathWorks Account credentials upon launching MATLAB.

license.dat

The license.dat is a processed license file that is created during the installation of the network license manager on the license server. When the network license manager is installed using the MATLAB installer, the license.dat is placed in the $MATLAB/etc folder (where $MATLAB is the installation directory).
The license.dat contains two additional lines at the top of the file, the SERVER line and the DAEMON line. These lines are generated by the installer and contain information specific to the machine the installer was run on.
The license.dat is used during the installation of MATLAB on network clients.
You can manually convert a license.lic to a license.dat by adding the SERVER and DAEMON lines and changing the file extension from .lic to .dat.
The syntax for the SERVER and DAEMON lines is as follows:

SERVER {hostname} {HostID} 27000
DAEMON MLM {$MATLAB}/etc/MLM

network.lic

The network.lic is created when a license.dat is provided during installation of a network client installation. Similarly, when a network client installation is activated using the MATLAB activation client, the network.lic is placed in the $MATLAB/licenses folder (where $MATLAB is the installation directory).
The network.lic contains two lines, a SERVER line and the USE_SERVER directive.
You can manually convert a license.dat to a network.lic by deleting everything but the first line and replacing it with the USE_SERVER directive.
The network.lic can be used instead of the license.dat for activation of a network client installation.
The network.lic is only used on network client computers.
The syntax for the file is as follows:

SERVER {hostname} {HostID} 27000
USE_SERVER

Please note that with the exception of the license_info.xml license file, these names are conventions, not rules. The exact names and functions of these files may vary depending on your local MATLAB configuration. Any questions related to your specific usage should be directed to your license administrator.

MATLAB: What ports does the Network License Manager use, and how can I set those ports

The network license manager requires two TCP ports for normal operation. The license manager contains two processes, the license manager daemon (lmgrd) and the vendor daemon (MLM). Each of these processes operate on a different port. The ports for each process are specified within the MATLAB license file on the license server. These ports are not locked and can be changed to any available TCP ports on the machine.

The port used by the license manager daemon (lmgrd) is used to listen for incoming license requests from the client application. This port is set to 27000 by default during installation. Once lmgrd is contacted by the client application, the vendor daemon (MLM) responds with the name and location of the vendor daemon and a second port number. The second port is used for communication between the client application and MLM. The MLM port is the one that is used for communication of license checkout and status requests. The port used by MLM is not set by default. When it is not set, the port is chosen randomly.

The ports of the license manager are specified within the license.dat file on the license manager machine. The license manager files are located in the MATLAB installation directory (on the server) in the flexlm folder on Windows (etc as of R2010b), and in the MATLAB installation directory in the etc subdirectory on all other systems. The port for lmgrd is set in the SERVER line of the license.dat file. For example, to specify port 27000, you would have the following:

 SERVER server1 8090bf8d 27000

To change the port, change 27000 to another number. It is recommended that you choose a value between 27000 and 27010.

The port assignment for MLM is specified in the DAEMON line of the license.dat file. By default this is not set. To change the port you can append "port=" and the port number at the end of the DAEMON line. For example:

 DAEMON MLM "C:\Program Files\MATLAB\R2018b\etc\win64\mlm.exe" port=1049

In this example, the port for MLM would be 1049. Specifying the port assignment for MLM can be useful if you are running the license manager through a firewall. In that case you will want to use specified ports so that these can be opened in the firewall.

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Related Solutions

MATLAB: What are the differences between the license.lic, license.dat, network.lic, and license_info.xml license files

MATLAB: What ports does the Network License Manager use, and how can I set those ports

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