Changes to VMs in Availability Set and Load Balancing

Question

I have gone through the whole process of testing and setting up two or even three VMs under availability sets and load balancing endpoints, and I have noticed how when accessing the domain the different VMs instances are loaded since I put different titles on each instance of a CMS web site to test the availability. The main reason I am trying to look into this is that the current VM/web site has had some problems when Windows did their periodical updates, which at times stopped the FTP or changed the server settings.

While this is working almost the way I thought it would, my question is about what happens when a client, who this will be setup for, makes changes to a CMS web site. My thought is that if they make changes to the CMS then those changes only apply to one instance of the VMs in the availability set, and if the VMs are load balancing where the different VM instances are loading then multiple different changes could be applied to each VM in the Availability Set.

What I am trying to determine but not coming across anything concrete, is if there is away to setup a shared network or system to mirror any changes to the each VM so that the web site stays consistent. Or if using the Availability Set for the current VM and web site is still applicable.

If anyone can give me some insight that would be great.

Answer 1

Is using the server's file system necessary for the CMS software? Could the CMS software read/write content to/from a database instead?

If using the server file system is the only option, you could probably set up a file share on one server that all the other servers would work against. This creates the problem though that if the primary server (that containing the file share) goes down for some reason, the site is as well.

Another option could be to leverage Web Deploy to help publish the content changes. Here are two blog posts that discuss this further:

• http://www.wadewegner.com/2013/03/using-windows-azure-virtual-machines-to-publish-and-synchronize-a-web-farm/
• http://michaelwasham.com/2012/08/13/publishing-and-synchronizing-web-farms-using-windows-azure-virtual-machines/

Answer 2

This really depends on the CMS system you're using.

Some CMS systems, especially modern ones, will persist settings in some shared storage, like SQL Server database and thus any actions that users make to the CMS will be stored in this shared storage and available to all web servers that are housing the CMS.

Other CMS systems may not be compatible with load-balanced web servers. Doing file sharing/replication/etc of the files stored on local servers may or may not work, depending on the particular CMS and its architecture. I would really try to avoid this approach.