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Question
Does anti-virus software have an impact on MIKE product performance?

Answer
Antivirus software having a negative impact on performance is a well-known fact – it can have a negative impact on both the general performance of a computer/image and a specific application.

The impact of the antivirus software depends on a few items:

  1. The application itself
  2. How the antivirus software is configured
  3. How the applications are utilized

There are many different antivirus products on the market, unfortunately we cannot test them all to have the detailed knowledge of how they work. The degree of negative impact may differ between the different antivirus products and the configuration of these, and we have no possibilities to evaluate.

The negative impact of antivirus software on performance is a 'penalty' of a high level of IT security. The risk evaluation and the level of IT security depends on the customers. We do not get involved with the IT security and IT policies and cannot guarantee the application will not be infected after they have been installed or produced on the customers systems.   

As the product vendor, we are aware of the potential negative effect of antivirus software on our software and especially a potential reduction in performance for e.g., MIKE FM simulations. It is our experience that the negative impact is primarily due to the antivirus software scanning output files, which are created and modified during a simulation. If this is the case, the performance can be improved by excluding output files from scanning by configuring the antivirus software accordingly. The most important candidates for exclusion would be the files with the extension of dfs0, dfs1, dfs2, dfs3 and dfsu, when doing MIKE FM simulations. Other file types may be relevant for other applications. Another approach is to exclude specific disk location from scanning (e.g., the simulation work directories of the simulations). However, please note that we do not make any specific recommendations due to the reasons mentioned above.
                                                                              
There are also a few ways to attempt to lower the performance impact. As output files are scanned when modified, the output frequency may be evaluated and limited to only the necessary output. In these cases, large output files are good candidates to look at and timeseries files (dfs0 files), since these often have the high output frequency. When running MIKE FM simulations in parallel mode, then quite often the number of subdomains or threads are set to the total number of cores available on the system. In this case there will be a MIKE FM process running on each core and all cores are fully loaded with work. If an antivirus application starts a scan (and thereby utilizing CPU), at least one of the cores will have to be shared in-between MIKE FM work and antivirus work. As a consequence the MIKE FM process running on this core will be slowed down - and accordingly the complete MIKE FM simulation, since the MIKE FM processes on the other cores will have to wait for the slow process. The impact on performance from this can be quite significant but can be limited by not utilizing all available cores for the MIKE FM simulation (e.g., number of available cores minus one). This may also be relevant in other cases depending on the job mix on the system. 

 

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