topic Re: License Server BackUp option in FlexSim Forum

License Server BackUp option

AmazonRobotics-123 — Wed, 21 Aug 2024 10:12:09 GMT

[ FlexSim 23.2.3 ]

We are planning for a FailOver / Backup server to help when license server goes down and have following questions.

1. Flexsim software send heart beat messages to the license server every 5 to 10 mins after seat is acquired?

2. If the license server goes down in the middle of model run (not build) what happens? We don't have any work to loose , as no modification is happening. Does the model still crash when running?

3. Is there a implementation recommended for fail over? ( Simple ping server or load balancer or any other option. )

Re: License Server BackUp option

Ben_WilsonADSK — Wed, 21 Aug 2024 13:49:20 GMT

Hi @AmazonRobotics-123

Please see FlexNet Publisher License Administration Guide Chapter 14. Ensuring License Availability (page 188).

Because FlexSim licenses are Trusted-Storage-based, only the option "Redundancy using the license search path" (page 188) is available. Essentially this means that your seats have to be spread across multiple license servers, and if one license server goes down, the seats that are hosted there are unavailable, but seats on other additional license servers that are still operational remain available.

So, if you have 12-seats, and spread them across 3 servers, you really will just activate 4 seats to each license server. Then if you lose one server, you still have 8 seats available while you work to restore the missing 4 seats.

In practice, a dedicated license server really does so little, and is so stable, that redundancy has never been an issue. My suggestion is just to maintain a single activated license server. If you really want, you could have a 2nd unlicensed server in reserve that is configured and ready to go, where all you'd need to do is reach out to our support team to recover your seats for activation to the 2nd server. However, I've never seen or heard of a backup license server being necessary or used.

I'm not sure the exact heartbeat interval. I've heard rumors of 15 minutes, but don't quote me.
The model won't necessarily crash, but if it uses any licensed features, those will revert to the free Express mode. See FlexSim Feature Limitations by License Type. For instance, reverting to Express means that the random number generator will become locked.
See above for failover options and details - spreading your seats over multiple license servers is really the only option. In the above example of 12 seats and 3 license servers, the client software would be configured to look for a license from any of the 3 license servers. If it can't contact one license server, or if the seats are all in use, it would move to attempt communication with the next license server, and so on.

Again, we just haven't seen that in practice a high-availability setup is necessary for a simple lmtools-based license server.

Re: License Server BackUp option

AmazonRobotics-123 — Sat, 24 Aug 2024 00:41:14 GMT

Issue is due to windows security / patches we have to take license server down and hence we need a backup license server to cater to the new jobs seamlessly. Is it possible to transfer the existing jobs to the new license server. Our jobs are running for 2 days and did not want to loose the two day of job.

Re: License Server BackUp option

Ben_WilsonADSK — Mon, 26 Aug 2024 17:24:26 GMT

You will need to determine best how to account for license server downtime and dividing your seats between multiple license servers or migrating all the seats at once, etc. Some of this may be trial and error to find the best workflow for your purposes.

Client PCs can be configured to get a license from the license server in one of two ways:

License Server - Licensing a single-user client PC (software interface)
License Server - Licensing a multi-user client PC (license file)

If you're using the single-user method, here is how to configure your FlexSim software to attempt to get a license from multiple license servers. Simply enter all available license server options, separated using a semi-colon, like this:

26914@lic.server.one;27001@lic.server.two;27009@lic.server.three

Here is an example image:

The software will attempt to contact each license server in turn until it obtains a seat or has attempted all license servers and failed.

In the example above, lic.server.one and lic.server.two are fully qualified domain names to properly configured license servers, with lmgrd serving on ports 26914 and 27001 respectively.

Re: License Server BackUp option

AmazonRobotics-123 — Tue, 27 Aug 2024 13:53:46 GMT

Thanks Ben, we are using the License File and not the software interface.

How do I add two ips to it example

SERVER 10.0.97.52 ANY 26914
VENDOR flexsim port=56914
USE_SERVER
FEATURE serverfeature flexsim 1.000 permanent uncounted HOSTID=ANY \
    SIGN="05CB 6F61 116D 06E3 A08D CAFB FC5C BEF3 DF53 BDC6 AF68 \
    060C 27B8 9968 CB94 0515 2BE7 E30C 2FAF C0D6 1D77 CCEB 878E \
    2D67 1434 0E3F 6BA5 1FDA BD35 F98D"%

I need to add the 10.0.98.213 as well.

Re: License Server BackUp option

joerg_vogel_HsH — Tue, 27 Aug 2024 15:49:11 GMT

asking an LLM-AI the answer is to insert additional SERVER lines.

Re: License Server BackUp option

Ben_WilsonADSK — Tue, 27 Aug 2024 17:21:44 GMT

@AmazonRobotics-123

This did not work for me:

In testing today, I found that adding multiple SERVER lines to the same license file prevented any license from being used on any server - it seems to break the license file, and the software makes no attempt at licensing via any of the servers listed.

Here is what works in my testing:

Instead, I found that creating multiple license files is the way to go.

So, in the directory

C:\Program Files\FlexSim <version>\program\

you will create a unique license file for each possible license server. In my testing using two license servers, I used two license files, named

license.lic
license (2).lic

In my case the software first tried to pull a license from the server designated in "license (2)" and only pulled from the server in "license.lic" when I changed the port designation to the wrong port in "license (2)". I don't know if it will always check servers in reverse alphabetical order of license files but that reflects my single experience with two servers and two license files.

Re: License Server BackUp option

Ben_WilsonADSK — Tue, 27 Aug 2024 17:43:04 GMT

I updated our articles with these learnings about using multiple license servers:

You can now find instructions there for pointing the software to multiple license servers.

Re: License Server BackUp option

AmazonRobotics-123 — Wed, 28 Aug 2024 14:39:45 GMT

Thanks Ben, will try this.

Re: License Server BackUp option

logan_gold — Tue, 03 Sep 2024 21:08:47 GMT

Hi @amazonrobotics-123, was Ben Wilson's answer helpful? If so, please click the "Accept" button at the bottom of their answer. Or if you still have questions, add a comment and we'll continue the conversation.

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