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Dynamics 365 Community / Forums / Microsoft Dynamics AX (Archived) / AOS Performance CPU/Me...
Microsoft Dynamics AX (Archived)
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AOS Performance CPU/Memory + scale out

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Posted on by Community Member

Hi, 

I have a customer that have one AOS 8 GB RAM, 4 Cores. They are about 180 concurrent users and experiencing performance issues in the AX client. The CPU utilization on the AOS is low and there is still free memory. It's NOT the SQL causing the issue and neither network issues. The SQL have good throughput to the SAN and the SQL can handle up to 3000-4000 batch request/sec without any problem. 

 

Will it help to Scale out the AOS even if the CPU utilization on the AOS is low? And this is the important part of the question. Why will it help and how do I explain why the CPU utilization low on the Server but they still need a new AOS?

 

I know that an AOS can handle 5000-15000 transaction/hour but why doesn’t it utilize the CPU more?

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  • Chino Profile Picture
    Chino 130 on at
    RE: AOS Performance CPU/Memory + scale out

    That depends on the cpu you use. The fact that you have 4 cores does not mean much as AX does not benefit from having multiple cores. You will get better performance from a single core with high mhz then 4 cores with a lower mhz per core. Did you try to make a trace dump and analyze the bottlenecks? 

  • Anton Venter Profile Picture
    Anton Venter 20,297 Super User 2025 Season 2 on at
    RE: AOS Performance CPU/Memory + scale out

    Hi Daniel,

    1. Can you give us more information about the performance issues with the AX client?
    2. Can you explain why you are saying it is not SQL?
    3. Have you monitored SQL / AX for slow performing queries?
    4. Have you monitored SQL for table locking?
    5. Are the SQL maintenance jobs up to date?
    6. If tables are locked, the SQL and AOS CPU usage will not be high as processes are waiting for locks to be cleared.
    7. Are you using (parallel) batch processing? If yes, what kind of processes run in batch?
    8. You will benefit from increasing the number of AOS severs because you can have more processes running in parallel in batch.

  • Community Member Profile Picture
    Community Member on at
    RE: AOS Performance CPU/Memory + scale out

    Lets leave the question about why they are experiencing performance issues and talk about the important part.

    Why is people recommending to scale out the AOSes even though the CPU utilization is low. Will it increase performance scaling out even though CPU utilization is low? And why will it help it that is?    

    I don't have all information but ill try to answer.

    • Can you give us more information about the performance issues with the AX client?
    • I haven't seen it myself yet, they are saying everything is slow, especially create/update rows.
    • Can you explain why you are saying it is not SQL?
      • Because nothing indicates that its a SQL issue that we can find. There´s no memory pressure, there are no locks and we see good throughput to the SAN, nothing we can see in perfmon indicates problem.
      • compatibility_level 110
        Cores 8
        fill factor (%) 90%
        max degree of parallelism 1
        Cost Threshold for parallelism 5
        Optimize for ad hoc workloads 0
        Server Collation Finnish_Swedish_CI_AS
        SQL Agent Account Domain Account
        SQL Server Account Domain Account
        SQL Version SQL Server 2012 STD Edition
        Trace flag: 1117 1
        Trace flag: 1224 1
        Trace flag: 4199 1
        Windows Authentication Mode Windows Authentication Mode
        Authentication protocol KERBEROS
        is_auto_close_on 0
        is_auto_create_stats_on 1
        is_auto_shrink_on 0
        is_auto_update_stats_async_on 0
        is_auto_update_stats_on 1
        is_parameterization_forced Forced
        is_read_committed_snapshot_on 1
        page_verify_option_desc CHECKSUM
        recovery_model_desc Full
        Auto Growth settings 200mb / 100mb -> Bad
        Power Balance High Power
        Event log No errors
        Alerts Serverity >16 and 823, 824, 825 No
        Ola Hallengren Yes
        Max Memory setting 26000mb
        LPIM 1
        TempDB 4 files, separate disk
         
    • Have you monitored SQL / AX for slow performing queries?
      • No, :/ 
    • Have you monitored SQL for table locking?
      • Yes, and there was no problem with locks. 
    • Are the SQL maintenance jobs up to date?
      • Yes, Ola Hallengrens scripts running daily (IndexOptimization). 
    • If tables are locked, the SQL and AOS CPU usage will not be high as processes are waiting for locks to be cleared.
      • No locks
    • Are you using (parallel) batch processing? If yes, what kind of processes run in batch?
      • I was just told that Batch and AIF is moved to new AOS and problem remains.
    • You will benefit from increasing the number of AOS severs because you can have more processes running in parallel in batch.
  • Martin Dráb Profile Picture
    Martin Dráb 236,320 Most Valuable Professional on at
    RE: AOS Performance CPU/Memory + scale out

    I'm really impressed that it's possible at all to handle 180 concurrent sessions with just 8 GB of memory. I would think it will consume much more.

    I can't say what's wrong with your system (and you can't fix it unless you find the problem. Let me just suggest a few other things to consider:

    • Look for issues related to client/server calls. Having a slow network and many C/S calls is a common problem that leads to perceived slowness of AX client.
    • Ensure yourself that you've configured AX and the database according to Microsoft recommendation (LCS system diagnostics can help with that). For example, sub-optimal configuration of number sequences can performance problems (although you should see them when monitoring database).
    • Performance Analyzer for Microsoft Dynamics could also find something interesting.

  • Verified answer
    Community Member Profile Picture
    Community Member on at
    RE: AOS Performance CPU/Memory + scale out

    I think that is always a big question : Scaling up versus Scaling out. Do you want to handle more load on the same server or you want to split the load on multiple servers ? The questions comes with different technology : AOS, Remote Desktop, SQL Server, SharePoint and I am sure you can find different topics on Internet on that question.

    I believe the two main reasons why you want to scale out an AOS are : redundancy and dedicate resource to a specific group of users/tasks.

    For instance, you may want to configure a dedicated AOS Cluster for Batch Groups.

    Another reason why you would like to scale out versus scale up is how the technology handles hardware resources (or maybe it has a resource limitation). We know that ESXi, Hyper-V, SQL are technologies that handle very well a lot resources ! I don't know any hardware limitation for the AOS, but I have never seen an AOS service taking more than 12GB or RAM, Microsoft recommends 2 GB per cores. Therefore, I would say that an AOS should be configured with 8 Cores / 16 GB maximum. I might be wrong here, it is just an assumption.

    Kind in mind that scaling-out doesn't only mean adding more vCPU or RAM to your machine, but you also need to consider the performance of those components. The CPU may not be busy, but maybe it is slow to compute. That is the difference between raising the speed limit or adding more lanes to your highway.

    I am also impressed that your AOS server has only 8GB of RAM.

  • dolee Profile Picture
    dolee 11,279 on at
    RE: AOS Performance CPU/Memory + scale out

    My 2 cents:

    •I haven't seen it myself yet, they are saying everything is slow, especially create/update rows.

    Talk with the user and setup a number of scenarios to look into. Look for issues that can be consistently reproduced. "Everything is slow" is too general IMO. Each issue that's slow can potentially be due to different reasons.

    Once the scope is scaled down (e.g. Posting sales invoice is slow), then AX Trace parser can be handy.

    Chances is, once you identified the cause of a few issues, you will know whether additional hardware is needed.

  • Klaas Deforche Profile Picture
    Klaas Deforche 2,433 on at
    RE: AOS Performance CPU/Memory + scale out

    Actually I'm not surprised that you 'only' have 8 GB of RAM. The sizing guidelines I got  (based on day in a life benchmark) say 60 users per core and 2 GB RAM per core for user AOSes. That makes 180 / 60 = 3 Cores and 3 * 2= 6 GB of ram. Round that to 4 core + 8 GB RAM machine (windows needs processing power and RAM too) and you got a correct sizing (based on DiaL).
    If this AOS is only used for users that is (so no batches, no EP, SSRS...). However the system requirements do recommend 14 GB of ram (LCS says 16 GB), so if you can, double the RAM.

    In my experience performance problems are rarely caused by the aos. Just make sure it is comfortable but don't overdo it either. In your case, if the CPU usage is low and there is free memory, it is doubtfull the AOS will be the bottleneck (my opinion).

    If your server is virtualized, the problem could be there. Maybe the "real" cpu is at 100% who knows.... or maybe the virtualization software has trouble finding 4 available cores to run your machine on... Adding cores to your machine will decrease your performance if that is the case, decreasing the number of cores may speed up your machine. But I'm not a virtualization specialist, so yeah, maybe someone was pulling my leg when they explained this to me :-).

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