Resource Monitoring and 452 4.3.1 Insufficient system resources in Exchange 2007 and SES

03/26/2020 1133 12345

DESCRIPTION:
Resource Monitoring and 452 4.3.1 Insufficient system resources in Exchange 2007 and SES

RESOLUTION:

With the added security and functionality of Exchange 2007 for Edge Transport/Hub Transport and the SMTP relay functions, you may see both on the Exchange Side in event viewer, and on the SES side in the MLFASGSMTP log, errors related to Insufficient System Resources, Too Many Errors on this Path or others. Specifically, in the Event Viewer on Exchange, The Application Event Log has Event ID 15002 from MSExchangeTransport saying "The resource pressure is constant at High. Statistics... ". The event goes on to tell you that inbound mail submission has stopped, and it's due to disk space being low on the volume where the queue database is located.

You may also notice symptoms similar to the following, where all inbound mail from other domains is stopped as well as the SES unjunk process on the ES not working. When you add an accepted domain in the hub transport settings, inbound email and un-junking for that domain works for that one domain but not others.

The first recommendation is to disable Resource Monitoring in the EdgeTransport.exe.config file located on your transport server's filesystem. Set the value for Resource Monitoring to FALSE rather than TRUE.

Second, you will want to verify that there is ample space on your Exchange 2007 server for the QUEUEING of email and the QUEUE directory.

Exchange Server 2007 transport queues are not the familiar .eml files you see in Exchange Server 2003/2000, which reside in the mailrootvsi <1>queue folder (<1> is the instance number of the SMTP virtual server) on the file system. Queues have been moved to a JET database.

The Transport service monitors system resources such as disk space and memory on Transport servers (the Hub Transport and the Edge Transport servers), and stops message submission if it is running low on those. It continues to deliver existing messages in the queue. When resource utilization returns to normal, it resumes message submission. The feature is called Back Pressure.

http://technet.microsoft.com/en-us/library/bb201658.aspx

Many configuration options for transport servers are saved in the file Exchange ServerBinEdgeTransport.exe.config (same name on Hub Transport servers as well). You can edit the file to disable Back Pressure, or modify the parameters to more accurately define what's high utilization for your deployment or server configurations.

The Back Pressure settings in Exchange Server 2007 stop inbound mailflow if free disk space is below 4 Gigs. This static threshold has been lowered in SP1 to a more realistic 500 Mb.

The Resolution

- Ensure that your Exchange server has 4 GB free on the volume where the queue database is located if you have not installed SP1 for Exchange 2007 on the server yet.
- The Queue database was moved to another volume with ample of free space, as documented in "How to Change the Location of the Queue Database"
- Once this is done, MSExchangeTransport service needs to be restarted, and message submission will resume.