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Load Balancing and Mirroring


Hi guys, I am setting up load balancing on EpiServer 8 for the first time, I've done a few builds but never been involved with this part of the setup. I not long ago had the proper training where Mirroring was mentioned but I just had a few questions if anyone can help that would be grand.

So our setup is a CMS box with 2 Web boxes, the firewall is doing the load balancing world. Would the recommended approach be setting up load balancing like and sharing the files/replicating or using Mirroring. A

As far as I was aware on the trianinging Mirroring was the correct way forward but I havn't found any great articles going in to it.



Oct 05, 2015 15:58

Hello Scott

Unless the client specifically needs a separate environment you should avoid using mirroing. Set up load balancing as described in the article but ensure that all three machines can comminucate over UDP. Add the CMS box as the edit/admin machine then let the two web front ends handle the public traffic. Ensure the edit/admin UI is removed on the two front end boxes:,-admin-and-util-folders-on-the-front-end-servers

Also check out this article on securing the edit/admin UI:


Edited, Oct 05, 2015 23:31

Thanks David. What are the scenarios that Mirroring is used then?. I've done load balancing a zillion times on EpiServer 6, Sitecore and Umbraco but it sounded very much when we did the EpiServer training like Mirroring was a replacement for traditional load balancing configuration? Can you elaborate?

Oct 06, 2015 9:43

Hi Scott

In general there are a couple of scenarios where mirroring is appropriate:

  • Security - if the organisation security policy means that content can only be edited on the internal network then it's appropriate as editors can work on their internal edit/admin box and let mirroring push the content changes live as/when they are made. 
  • Regulated environments - where an entire copy of the site needs to be signed off by the regulation department before it can go live. Typically mirroring will be timed or manually triggered in these scenarios. 
  • Content sharing - specific channels can be set up to share content between EPiServer environments (for example news items on different brand sites). 
  • Geographic distribution - in some scenarios customers may wish to have physical infrastructure in different parts of the world to reduce latency or comply with local laws/regulation (e.g. China)  
  • Large scale/resiliency - it's possible to set up independent clusters to serve the site. In this scenario each cluster may be in a physically different data centre and global load balancing is used to route traffic. In this scenario mirroring is used to push content to each cluster and means it's possible to lose an entire data centre and still operate your site. 

However it's worth bearing in mind that mirroring has inherent complexities so adds additional configuration, deployment and QA time to projects. Also mirroring isn't supported on Digital Experience Cloud (DXC) Cloud Configuration. 

DXC is cloud hosted and uses a CDN to remove the reasons for some of the items above. Also the new Projects feature can also do away with some of the other reasons such as when used in a regulated environment as it's possible to preview the entire site with multiple changes. 

My honest advice would be to think hard before using mirroring.  


Oct 06, 2015 10:35

Thanks for the update, that all makes sense. For this project standard load balancing will suffice but I can see those scenarios being useful for some of the projects we have worked on should they have been EpiServer and not Sitecore. I'll keep note for future projects.

Thanks again.

Oct 06, 2015 11:15
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