SharePoint 2013 stretched farm latency

Question

I'm planning to stretch our SP farm. I'm going to move 1 WFE and 1 APP to another data center. Distance between data centers less than 10 km.

Based on this article there are strong requirements:

For a stretched farm architecture to work as a supported high-availability solution, the following prerequisites must be met:

There is a highly consistent intra-farm latency of <1ms one way, 99.9% of the time over a period of ten minutes. (Intra-farm latency is commonly defined as the latency between the front-end web servers and the database servers.)

The bandwidth speed must be at least 1 gigabit per second.

The question is - What if sometimes latency between remote WFE and DB server will be 3 or 4ms? Several times during 10 min period the latency was 3 ms.

What it will cause? Only low performance or something more?

Answer 1

In general, this won't be an issue but you may run into support problems if you open a case with Microsoft if you cannot demonstrate that level of response time.

The general recommendation is to not stretch farms, instead implementing a DR farm (though 10KM is a very short distance where a major geological event or similar would likely impact both locations).