The SLiM translator writes log files into the CEI/license8/ folder. The SLiM translator service may fail when using Windows Services if it does not have permission to write to that folder. The current workaround is to allow write access to the CEI/license8/ directory or change the service's start parameters to add -l DIRNAME to specify a folder where logs should be written.

Background

EnSight and related tools run on all three major desktop platforms: Windows, Linux, and macOS. Since Ansys licensing is supported only on Windows and Linux, another solution was required to support macOS. Before CEI was purchased by Ansys in 2017, it used an in-house licensing system called SLiM (simple license manager) across all three platforms. From 2017-2021, Ansys continued to support SLiM as the primary licensing mechanism for macOS (and as a backup licensing mechanism on Windows and Linux).

As of the 2021 R2 release, it was desired to retire SLiM as a licensing mechanism and move entirely to Ansys licensing. This document details the SLiM-to-Ansys licensing translator that we developed to continue to support macOS as a platform.

SLiM Translation Daemon

The slimd8 (or slimd8.exe on Windows) daemon serves the role of SLiM server, listening on a socket for SLiM clients and serving those licensing requests. In prior releases, it had a key file that defined what features it was responsible for and how they should be handled (what client machines were valid, what time periods were covered, etc.)

The new slimd8 (or slimd8.exe on Windows) in 2021 R2 looks the same to SLiM clients. It sits on the network, waiting to serve client requests. But instead of checking an internal database of features, it instead forwards feature requests to an Ansys license manager. The underlying SLiM network protocol has not changed, allowing even older clients to operate with the new SLiM "translation" daemon. This also means that the new slimd8 no longer reads SLiM key files since there is no longer a concept of an internal feature database to manage.

SLiM Features and Ansys Licenses

Though the SLiM daemon can manage features of any name (and there are many in SLiM history), only certain feature names are translated when talking to the Ansys license manager. All other feature names are rejected. The valid feature names are ensight, ensightgold, cfd_preppost, and envisionpro. We could add to the list in the future should licensing demands require it, but these are the license names currently supported in 2025 R1.

SLiM continues to support a heartbeat concept, with the SLiM translator daemon expecting to hear back from every SLiM client it has issued a license to every so often. By default, it assumes that clients will check in at least every 10 minutes. If the translator does not hear back from a client, it internally marks its license as having temporarily timed out. If the client reappears in time, the license is marked as being okay. However, at the top of every hour, the translator will check in any licenses that are still marked as timed out. If, perchance, the client reappears after the license has been checked back in, the SLiM translator will attempt to check the license back out but runs the chance of having that license no longer available at the Ansys license manager. In this case, the client will be denied the re-checkout.

SLiM continues to support server redundancy. If multiple SLiM servers are set up, a SLiM client (like EnSight) that is configured to see multiple servers will try them in order. If the first server does not accept the connection, the client will automatically progress to the second, and so on.

SLiM Configuration and Operation

The existing bin/slimd8_* scripts operate with the new SLiM daemon, except that any SLiM key file argument has been removed. Thus, slimd8_start will check if an old process is around, kill it if so, and then starts a new SLiM translation daemon. The slimd_status script works the same as it did before. The slimd8_stop script also operates without changes.

The SLiM translation daemon is configured using two environment variables, SLIMD8_SERVERS and ANSYSLMD_LICENSE_FILE.

Compatibility

The SLiM protocol has not changed with the introduction of the SLiM translation daemon. This maximizes compatibility between versions, allowing older EnSight releases to communicate with current SLiM license servers. However, the new SLiM translation daemon does not recognize or serve up any type of SLiM key files, so any floating SLiM keys a customer may have will need to be converted into standard Ansys license keys. EnSight 2021 R2 itself still recognizes node-locked SLiM keys, but a future version of EnSight will remove this support. Please begin the process of converting your SLiM keys to standard Ansys licenses.

Platform Requirements

Due to the requirement of loading the Ansys licensing libraries, the new SLiM translation daemon runs on Linux and Windows only. There is no macOS version. Indeed, the SLiM translation daemon was created to provide customers a bridge from macOS clients to the main Ansys licensing system. With this release, SLiM keys are retired.

Example Configuration

As a tangible example to illustrate what needs to run where, with what environment variables, and what the expectations are, the following basic example is used for demonstration.

Beginning at 2021 R2, customers purchasing License Bundles (CFD Premium, CFD Enterprise, CFD PrepPost) will experience a change in their increments within the license file. No longer will there be explicit ensight or ensight_enterprise increments included. Instead, EnSight will now utilize and check-out the cfd_preppost license, and will automatically start up EnSight Enterprise for you. The change in increments has been made to better align the intended use of EnSight in the context of other applications enabled within the cfd_preppost increment. In order for EnSight to utilize the new cfd_preppost increments, users will need to be using EnSight 2021 R2 or later. If you have not already updated to 2021 R2, but receive these reduced increment license files, contact your sales/account representative. There is a temporary promotion in place to re-issue license keys with explicit ensight or ensight_enterprise increments until you have migrated up to 2021 R2 software versions.

EnSight and EnSight Enterprise can still be purchased separately, and their license increments are still ensight and ensight_enterprise.

Customers with extra or separate EnSight licenses purchased, will still receive a license file including explicit ensight and ensight_enterprise increments.

If customers have both stand alone licenses and bundled licenses, EnSight will look to consume its own stand-alone licenses (ensight or ensight_enterprise) before looking to consume and cfd_preppost increments.

Migration Issues

The following situations are known/expected issues which are part of the migration from the old method of increments into the new increments:

In EnSight 2023 R1, the Ansys License Manager (Ansys LM) allows idle licenses to be made available for subsequent use by new sessions of EnSight. An example of a use case would be your EnSight session going idle during meetings or overnight. The idle license is then made available for a new session of EnSight to utilize that license such as a batch EnSight job at night. Once the formerly idle session of EnSight is made active again, it attempts to check out a new license to continue with its interactive operation.

Functional Operation

To utilize this capability, the following features and conditions need to exist for this functionality to work: