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Outstanding RPC requests reached maximum threshold

[This topic is intended to address a specific issue called out by the Exchange Server Analyzer Tool. You should apply it only to systems that have had the Exchange Server Analyzer Tool run against them and are experiencing that specific issue. The Exchange Server Analyzer Tool, available as a free download, remotely collects configuration data from each server in the topology and automatically analyzes the data. The resulting report details important configuration issues, potential problems, and nondefault product settings. By following these recommendations, you can achieve better performance, scalability, reliability, and uptime. For more information about the tool or to download the latest versions, see "Microsoft Exchange Analyzers" at https://go.microsoft.com/fwlink/?linkid=34707.]  

Topic Last Modified: 2006-02-13

The Microsoft® Exchange Server Analyzer Tool includes a performance data collection engine that is used to query performance counter objects on computers that are running Exchange 2000 Server or Exchange Server 2003. The performance data collection engine collects data from the RPC Requests performance counter of the MSExchangeIS performance object to analyze performance data.

If the Exchange Server Analyzer determines that the number of RPC requests has reached the peak value of 100 during the sample time slice, the Exchange Server Analyzer displays an error.

The RPC Requests performance counter indicates the number of MAPI remote procedure call (RPC), or client, requests that are currently being processed by the Microsoft Exchange Information Store service. The average value of the RPC Requests performance counter should be under 30 at all times. By default, the maximum value for RPC requests is 100. Therefore, unless it is configured otherwise, the Microsoft Exchange Information Store service can service only 100 RPC requests at the same time before all new RPC operations will be rejected and users will not be able to connect to the server until the RPC requests drop below 100. The server will become unresponsive, mail flow may stop. The Outlook users may receive the RPC cancel Request dialog box.

This error indicates that the server is experiencing a performance bottleneck or that a process has stopped responding.

A performance bottleneck may be CPU, disk, network, or memory related and can be caused by an increase in load to the server or insufficient server resources. Use the Performance Monitor (Perfmon.msc) tool to determine whether the bottleneck is caused by an increase in load to the server or if the server is undersized. If the server load has increased, identify the source of the load and reduce it. If the server has insufficient resources, increase the necessary resources or move users off the server.

A process might stop responding because the store is waiting for a resource that never returns. Examples would be a cluster losing the drive that hosts message tracking or a virus scanner problem. When a process stops responding, RPC requests will never drop back down, and the store must be restarted.

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