What are pros/cons for not to use Redis in Clustered Orchestrator?

Hi there, I am planning Orchestrator setup with High Availability however Redis is not a good option for now.

One of the document from version 2016.2 stated that we can use MSSQL to store Session information instead of Redis

This doc topic 2) https://orchestrator.uipath.com/v2016.2/docs/cluster-installation

Is this option still possible for 2018.4 version?
What are pros/cons for storing session information on SQL Server instead of Redis?

Thanks.

Redis is mandatory in a cluster environment. Setting up the Orchestrator in a clustered environment without a Redis Server is not supported by UiPath.

So I don’t think you have any options here, unless you are willing to go out of support by UiPath for any issues.
using SQL DB for session management will have performance issues.

you could ask UiPath support for documentation on installing Redis, they are pretty good.