AX 2012 R2 AOS and High CPU usage

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Posted on by Dalibor Sinik

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Need little help with AX 2012 R2 and AOS that are using much CPU 75-100%. In DEV database there are lot of customizations and one day AOS begin to use lot of CPU, using constant 75-100% CPU on 4 cores.

Developers have turned off customizations but still when example forms are opened AOS starts to begin using lot of CPU.

When user close down AX client I can see under Online sessions that user have status Ending - Blocked, I cannot end session, the only way is to restart AOS.

Any ideas how to troubleshoot this?

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Brandon Wiese 17,788 on at

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High CPU usually means the AOS is busy executing code and not calling SQL Server, but generally when I see Ending - Blocked then the AOS is waiting on SQL Server for something, so it is not clear up front which is really the case.

In case the AOS is waiting on SQL Server, you can check --

On the SQL Server host, open up SQL Server Management Studio. Then open the Activity Monitor (Ctrl-Alt-A), and expand the Processes section.

Look for items with a task status similar to SUSPENDED, i.e. not blank and not RUNNING. Also, it may be that something is RUNNING for a long time, so look there last. You should be able to right click on any persistent row and inspect its SQL statement, which may provide clues about what it is doing. You can also Kill processes in SQL Server, though you should do so with great care and at your own risk.

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In addition to the tools Brandon mentioned above, you can look at several different DMVs or procedures. Two of my favorites are sp_AXWHO and sp_WHOISACTIVE. I would also analyze perfmon counters in order to try to localize exactly what is causing things to back up.

Some questions for you:

1) Do the processes ever finish successfully?

2) If so, Is the timeframe of completion acceptable?

3) Is your AOS/SQL Server adequately sized for your workload?

4) Are you on a SAN?

5) Is your SQL Server virtualized?

There are many more questions I could ask here, but these are a few of the big hitters to start with. The fact that you turned off the customizations in order to try to localize the issue is a good first step, but I would need to know more in order to understand the problem better.

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Brandon Ahmad 2,465 User Group Leader on at

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This is always a tough question to answer from a forum post. There really are so many things that can cause it and a forum paragraph is barely enough to get you started. In this case, our gentlemen have very good suggestions.

If I were starting, I would make sure that I had the core performance counters setup. That will do a lot to hone you in to the problem.

Here is a good tutorial with the core performance counters that should be running in your Dynamics AX installation.

www.brentozar.com/.../dba-101-using-perfmon-for-sql-performance-tuning

Again, that is just a starting point. You may find something simply by using the intimate knowledge that you've gained from working with the environment -- knowledge that would be impossible to share in one paragraph on a forum.

But the Performance Counters on SQL Server are a strong start that I often see lacking in Dynamics AX installations.

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Dalibor Sinik 170 on at

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Hi,

I went through the whole Environment, VMware, hardware, SQL server and could not find some performance problems or locks in SQL.

I set up new instance from and older DEV DB backup and imported CUS model and the problem came back :(

There is something about CUS layer.

Next step was to setup new DEV from TEST and the developers imported customizations (.xpo) and everything works normal.

Strange problem :)

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JoeHowen on at

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We are in the process of rolling out new AOS servers for our European launch and are encountering the same issue. The new AOS service is pegging the CPU utilization and it is not an issue with the database. SQL Load is not a problem at all. No blocking, no high resource utilization on the SQL Server and the current AOS servers handle the processing load fine.

Environment: AX 2009 RU 8

AOS Servers (Original) Windows Server 2008 R2 Standard - Batch processing Runs fine

AOS Servers (New) Windows Server 2012 R2 Standard - AOS Service pegs CPU and processing runs 10 times longer.

Also: The new AOS servers are essentially non responsive when the service is running and processing batch job threads.

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neeti 12 on at

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HI Joe,

Did you find a resolution for this ?

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JoeHowen on at

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Hi neeti, Additional research showed that while Microsoft supports SQL Server 2012 for an AX 2009 implementation, it does not support Windows Server 2012 for AOS servers. (At least it did not the last time we checked) AX 2009 AOS System requirements do not explicitly prohibit 2012 but when we met with Microsoft support, they indicated that Windows Server 2012 was not supported. We rebuilt the new AOS servers using Windows Server 2008 R2 and the problem was resolved. Hope this helps.

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