User guide

Chapter 4 - Selecting License Server Machines
Redundant License Server Systems
42 FLEXnet Licensing End User Guide
The user in Chicago could set LM_LICENSE_FILE to:
1700@chicago:1700@tokyo
The user in Tokyo could set LM_LICENSE_FILE to:
1700@tokyo:1700@chicago
Remember to separate the license file names with a colon (“ : ”) on UNIX and with a semicolon
(“ ; ”) on Windows. The application attempts the first server in the list, and if that fails for any
reason, the second server is tried.
Three-Server Redundancy
The machines that comprise a three-server redundant configuration are required to have
excellent communications. This form of redundancy requires that the servers exchange
heartbeats periodically, and poor communications can cause poor performance. Avoid
configuring redundant servers with slow communications or dial-up links.
Three-server redundancy is designed to provide hardware fail-over protection only and does not
provide load-balancing. Use
LM_LICENSE_FILE list, instead, if load-balancing is desired. This
is because with three-server redundancy, only one of the three servers is “master,” capable of
issuing licenses. Since all clients must contact the “master,” all clients must have reliable
networking to a single machine. For more details, see “Three-Server Redundant
Configurations.”
Comparing Three-Server to License-File List
Are there any drawbacks to using the license-file list for redundancy?
Yes. By default, once a FLEXenabled application has successfully checked out a license from
a given license server system, all subsequent license requests from the same application must
be satisfied from the same server system. In the event that the application makes subsequent
license requests and no more licenses are available from that server system, the license request
is denied even though licenses may exist on another server. An application can bypass this
restriction if it is coded with the use of multiple FLEXnet license jobs. Only your publisher
knows if their application is programmed in this manner.
If the application supports license queueing, all licenses are queued only from the first license
server system on the list rather than the request moving to another server on the list.
Finally, if one server becomes unavailable, some licenses are unavailable.
When is it recommended to use a license-file list for redundancy rather
than three-server redundant servers?
• When there’s less system administration available to monitor license server systems.
• When load-balancing is needed for FLEXenabled applications located far apart, e.g.,
London and Tokyo, make servers available locally, with remote servers available as
backup.