Internet Information Services (IIS) is Microsoft's web server software that is installed as a role in Windows Server. IIS will be enabled and configured by the Orion NPM installer without any intervention or manual configuration needed by an administrator after the installation has completed. The only catch is that the IIS role must not be installed or enabled on the target Windows Server.

It is best to remove the IIS role from the Windows Server using the Server Manager application if it is enabled, since Orion NPM will replace the default IIS website with its own. Do this so that the Orion NPM installer is able to automatically configure IIS correctly. If the IIS role remains active, it is highly possible that the Orion NPM installation will fail.

Although it is not required, SolarWinds recommends installing Orion NPM and SQL Server on two different servers on different physical hardware for performance reasons. This recommendation is especially true if you are running SolarWinds and SQL Server in two different virtual machines on the same virtual server host, or if you plan on monitoring more than 100 nodes. Consider the fact that the Microsoft IIS service, the Orion NPM polling engines, and SQL Server processes are incredibly resource-intensive. Installing SQL Server and Orion NPM on the same server, even with less than 3 GB of RAM and a slower processor, might work fine for very small networks (less than 50 monitored nodes), but it is still not recommended to do so.

Orion NPM includes tools that will help you move the Orion database to a different Microsoft SQL Server instance if the need arises. This allows you to initially start with a single Windows Server with both Orion NPM and SQL Server installation on the same machine, then move the database at a later time or when performance becomes an issue.

The official stance from SolarWinds is that SQL Server Express editions are supported, but SQL Server Standard or Enterprise editions are highly recommended. The reason being SQL Server Express editions have been handicapped by Microsoft. SQL Express cannot utilize more than 1 GB of system RAM on the Windows Server where it is installed. This is true regardless of how much RAM is available on the server. SQL Server Standard editions can use up to 16 GB of available system RAM and Enterprise editions can utilize as much RAM is available to it on the Windows server. Also, SQL Server Express technical support is only available by Microsoft through the TechNet and community support forums while the Standard and Enterprise editions are supported under regular support contracts.

With all of this in mind, SolarWinds ultimately leaves it up to the administrator to decide if they want to use a limited edition or an officially-supported business edition of SQL Server. Selecting an appropriate SQL Server edition depends on how many nodes you intend on monitoring with Orion NPM, as well as what you consider an acceptable risk regarding technical support. So the question remains, "Which SQL Server edition should I choose?" Based on my personal experience, you should use the following: