Tableau Server on Windows Help

The VizQL Server loads and renders views, and computes and executes queries. To achieve high availability for the VizQL Server process, configure one or more instances to run on multiple nodes.

Process	VizQL Server
Status	Status of theVizQL Server process is visible on the Status Page. For more information, see View Server Process Status
Logging	Logs generated by theVizQL Server process are located in C:\ProgramData\Tableau\Tableau Server\data\tabsvc\logs\vizqlserver. For more information, see Tableau Server Logs and Log File Locations

What happens if a VizQL Server process fails? If there is only one VizQL Server process and it fails, then Tableau Server will no longer be able to render any views. High availability requires configuring redundant VizQL processes. A fairly typical configuration consists of two to four VizQL Server processes on each node.

This simultaneously serves the need for high availability and scalability. If multiple VizQL Server processes are running, then the failure of a single process will result in the failure of any requests and the loss of session data at the time of its failure. Any future requests will be routed to the other working VizQL Server processes on the Tableau Server cluster.