I rate the tool’s scalability an eight out of ten. In our organization, at least 15 different systems have the product. Around eight people use the solution.

More than 100 users are using the solution. We cater the solution to medium to large businesses.
I rate the solution’s scalability a six out of ten.

Windows Server Failover Clustering is a scalable solution.

We have approximately 100 users using this solution in my organization. Some of their roles are IT integration manager, system administrator, and security teams.

The solution is scalable. If you want to create a cluster of servers, you need to install and deploy the Windows Server Failover Clustering service in each one of them. When you join one server to a cluster, it'll be a switch forward for the other server to join the cluster. You only need to configure the new servers you want to add to your cluster. 

Failover clustering can scale up and scale-out, depending on the exact solution. In a typical use case, which is a two-node RDBMS with shared disks, the scalability of each node (CPU, RAM) and the used storage system sets the limit.

The scalability of the solution is good. If an organization needs to scale up, it shouldn't have any issue doing so.

I would rate Windows Server Failover Clustering's scalability a nine out of ten. We use the solution three to four days a month. 

It scales without issue.