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Exchange Server 2007 Transport: 452 4.3.1 Insufficient system resources
Posted by Bharat Suneja at 5:24 PM
In my hotel room in Orlando, getting ready for a presentation tomorrow morning at TechMentor. When trying to telnet to the SMTP port of an Exchange Server 2007 Hub Transport server, I got the following error:
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.
Figure 1: Event ID 15002 logged by MSExchangeTransport
Exchange Server 2007 transport queues are not the familiar .eml files you see in Exchange Server 2003/2000, which reside in the \mailroot\vsi <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.
Back Pressure
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.
- Many configuration options for transport servers are saved in the file \Exchange Server\Bin\EdgeTransport.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, as explained in the above docs.
- In the above case, it seems it needs 4 Gigs free on the volume where the queue database is located - I have about 3.95 Gigs. :)
- 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 was done, MSExchangeTransport service was restarted, and message submission resumed.
Related Posts:
- Exchange Server 2007: How to turn off the Back Pressure feature on transport servers
452 4.3.1 Insufficient system resources
Not a good thing the night before a presentation - Murphy's law at work again!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.
Figure 1: Event ID 15002 logged by MSExchangeTransport
Exchange Server 2007 transport queues are not the familiar .eml files you see in Exchange Server 2003/2000, which reside in the \mailroot\vsi <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.
Back Pressure
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.
- Many configuration options for transport servers are saved in the file \Exchange Server\Bin\EdgeTransport.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, as explained in the above docs.
Changes to Back Pressure settings in Exchange Server 2007 SP1
The Back Pressure settings in Exchange Server 2007 RTM 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.
- In the above case, it seems it needs 4 Gigs free on the volume where the queue database is located - I have about 3.95 Gigs. :)
- 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 was done, MSExchangeTransport service was restarted, and message submission resumed.
Related Posts:
- Exchange Server 2007: How to turn off the Back Pressure feature on transport servers
Labels: Administration, Exchange Server 2007, SMTP
6 Comments:
Understanding Back Pressure
Thank you for your post. It helped me see why in my test virtual environment I couldn't send not even an e-mail (and was wonderring for some time now what I did wrong .. my VM had 10 Gig hard drive and it had only 3.9 Gig free :( )
So what is the unit for PercentageDatabaseDiskSpaceUsedHighThreshold? I set it to 1024000000 (1GB?) and restarted MSExchangeTransport and still got 15002 errors with mail stuck in the outbox. I finally just turned off backpressure altogether but am wondering if I set the threshold incorrectly in the config file.
Hi TimH,
Please refer to the BackPressure documentation (also linked in the above post). Look at Table2 that lits these parameters. The valid values are listed.
As the term PercentageDatabaseDiskSpaceUsedHighThreshold states, it's not an absolute value (in memory units) but a percentage.
Thank you for attempting, my problem was it that you solved.
Best regard
Alireza Soleimani
Thank for your Post.Previously i am not able send mails after reading your post i rectified problem.Thank you very much.
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