This metabase property specifies the maximum number of concurrent sessions that IIS will permit. If a client attempts to establish a new session with IIS once this limit is reached, the client will receive an error (HTTP 500 "Server Too Busy").
Note
ASP incurs a certain amount of memory
overhead for each session maintained. Although you could use
AspSessionMax to limit this memory overhead, it is generally
more appropriate to manage the lifetime of session objects within
IIS by using the AspSessionTimeout property, so that client browsers will be
rejected once the limit is reached.
If an incoming request doesn't have an ASP session cookie, or has a session cookie that doesn't match an existing session, it is considered a new session request. The Web service setting for this property is applicable to all in-process and pooled out-of-process application nodes, at all levels. Metabase settings at the Web server level or lower will be ignored for in-process and pooled out-of-process applications. However, settings at the Web server level or lower will be used if that node is an isolated out-of-process application.