Single Distributed Cache - What are the risks? Is it necessary?

Question

My experience with SP has been with 2010 so I am catching up on the new features and recommendations for SP2016. One of them is the distributed cache, and how it will benefit our users.

We intend on using SP as a replacement for our current eDMS, and leveraging other features within SP2016 to improve collaboration but to a limit. Social features will be offloaded to our SP Online solution as this will be a hybrid implementation, and we would prefer to run this on premise farm as lean as possible.

Reading more into it I am seeing that the recommendation is for up to three cache servers, which increases the footprint of this farm. The one thing I cannot determine is the risk with a single distributed cache. In the event a DC server goes belly up, what is the overall impact to the farm? Is it even necessary for a DC when you are minimizing the use of social features?

Answer 1

Distributed Cache is not only handling the social data but Security Trimming, news-feed, one-note client access, page load performance and authentication. Also there are many caches which rely on the Distributed cache. read "Different caches that depend on the Distributed Cache service"

System events, such as a power failure or unexpected restart of a server, affect the Distributed Cache service. Also, a planned activity, such as an administrator shutting down an application server that is running the Distributed Cache service to perform operational tasks, affects the Distributed Cache service. These actions reset and empty the Feed Cache and the Last Modified Time Cache

Apart from that, if Distributed cache server is down then user will get the access denied error. Now new authentication token being issued. Single DC server is little risky. Sites may be loading slowly if no dc server available for the farm.