Private bytes consumption changed from %1 to %2. Statistics: %3

Product: Exchange
Event ID: 15003
Source: MSExchangeTransport
Version: 8.0
Symbolic Name: PrivateBytesUtilizationChanged
Message: Private bytes consumption changed from %1 to %2. Statistics: %3

This Warning event indicates that the memory that is used by the EdgeTransport.exe process on a Hub Transport server or an Edge Transport server has experienced a change in utilization level. This system resource is known as private bytes consumption and is monitored as part of the back pressure feature that monitors utilization levels for system resources.

For private bytes consumption, the following levels of resource utilization are applied:

  • Normal   The resource is not overused. The server accepts new connections and messages.

  • Medium   The resource is slightly overused. Back pressure is applied to the server in a limited manner. Mail from senders in the authoritative domain can flow. However, the server rejects new connections and messages from other sources.

  • High   The resource is severely overused. Full back pressure is applied. All message flow stops, and the server rejects all new connections and messages.

User Action

If the event indicates that the private bytes consumption level decreased from High to Medium or from Medium to Normal, no user action is required. If the event indicates that the private bytes consumption level increased from Normal to Medium or from Medium to High, you can perform the following actions:

  • Do nothing. The back pressure feature will stop accepting new messages and connections on the server. Existing messages will be delivered until the private bytes consumption level on the server returns to Normal.

  • Install more memory in the server. By default, the High level of resource utilization for private bytes consumption is 75 percent of the total physical memory or 1 TB, whichever is less.

  • Increase the default values of the Normal, Medium, and High resource utilization levels for private bytes consumption.

For more information about back pressure, see Understanding Back Pressure.

If you are not already doing so, consider running the tools that Microsoft Exchange offers to help administrators analyze and troubleshoot their Exchange environment. These tools can help you make sure that your configuration is in line with Microsoft best practices. They can also help you identify and resolve performance issues, improve mail flow, and better manage disaster recovery scenarios. Go to the Toolbox node of the Exchange Management Console to run these tools now. For more information about these tools, see Toolbox in the Exchange Server 2007 Help.


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