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How many server nodes can you create per instance

Hi,

Very often the bottle neck in a java installation (NW04s) is the heap size. In order to increase the heap you simple create new server nodes.

My question is:

How many server nodes can you create per instance?

Is there an upper limit before you have to create a new dialog instance (with a web dispatcher)?

I can imagine that when you create a new server node you also have to increase the heap and max therad of the dispatcher. Is there any upper limit of the heap size of the dispatcher node ?

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  • Posted on Jun 29, 2009 at 11:35 AM

    Hi

    > My question is:

    >

    > How many server nodes can you create per instance?

    This depends upon your hardware size like RAM, CPU etc..

    > Is there an upper limit before you have to create a new dialog instance (with a web dispatcher)?

    > I can imagine that when you create a new server node you also have to increase the heap and max therad of the dispatcher. Is there any upper limit of the heap size of the dispatcher node ?

    Check SAP Note 723909 - Java VM settings for J2EE 6.40/7.0

    Thanks

    Sunny

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    • Hi Sunny,

      NW 7.3 SP 7.

      I have 32 GB RAM and 8 CPU for my EP CI server and the same for my Dialog Instance.

      When I added another Server Node to the instance the Portal turn slow.

      It does not makes sense but probably is because of JVM Settings that has to be adjusted.

      Global Area: 1

      InitialHeapSize 2048

      MaxHeapSize 2048

      MaxNewSize 410

      MaxPermSize 1024

      permSize 1024

      I added in configtool --- set value to 2-- save -- restart

      Any Clue?

  • author's profile photo Former Member
    Former Member
    Posted on Jun 29, 2009 at 11:36 AM

    I believe you can add upto 16 nodes but make sure you have enough resources (e.g. memory)

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    • Former Member Former Member

      Did you try to increase initial heap size (Xms) parameter? This decides the frequency of garbage collection cycle, amount of heap growth before new cycle starts. Too many GCs consumes CPU so you have to fine tune.

      hope this helps.

      Manoj

  • author's profile photo Former Member
    Former Member
    Posted on Jun 30, 2009 at 08:20 PM

    Quoted as:

    Proper number of server nodes within an instance:

    u2013 Configure JVM heap according to Note 723909

    u2013 #ServerNodes = availableMemory / (JavaHeapPermSpaceStack)

    Please refer to [http://service.sap.com/performance|http://service.sap.com/performance]

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  • author's profile photo Former Member
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    Posted on Jul 03, 2009 at 07:05 AM

    Hello,

    Calculation for number of server nodes goes like this,

    No. of server Node = (RAM you want to assign or available RAM in GB)/2.5 ============> for 64-bit system

    No. of server Node = (RAM you want to assign or available RAM in GB)/1.5 ============> for 32-bit system

    Hence as per above discussion, we should go with 5 server nodes means,

    5 = RAM/2.5 ( Assuming you are on 64-bit platform)

    i.e. RAM = 12.5 GB.

    Also this depends upon what all usage types you are using in your system.

    If you want all usage types should be in system i.e. AS JAVA, EPC, EP, BI and DI ( PI is not included), then it will be good if you use system with 16GB RAM and five server nodes.

    Please also update if you are now with more info, so that all of us gets update.

    Regards,

    Abhay

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    • Former Member Former Member

      Rasmus , I think you laid out a real good scenario for every one to contribute

      I may be very late but just updating this forum for benefit of everyone who visits this.

      In addition to all the points above one must also consider following things if one decides to add more server nodes to one dispatcher

      1.Garbage collection time

      2.Dispatcher would keep on sending request to node S2 if it is not completely bad and there by impacting all the servernode so you might end up restartiing the entire cluster.

      3,Debugging also becomes diffculy as you are not sure on which server node you are within the cluster.

      4.If you have something like F5 which does hear beat monitoring even one server node goes bad F5 will not report anything.

      So in my view one server node per dispatcher is an ideal configuration.

      Over All Dispatcher does not consume more resouces (Disk Space + CPU + memory ) at the same time it will give you maintenance flexibility.

      Nothing is right or wrong ,all these things are based on how your infrastructure set up is.

      Cheers !!

      Manish Jain

  • author's profile photo Former Member
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    Posted on Nov 15, 2011 at 05:18 PM

    Hi All,

    Officially there is no limit to the amount of server nodes you can add, If you have available the memory and cpu you can keep adding server nodes.

    Manish point #2 above though is relevant when adding more nodes. From experiance I would a maximum 5 or 6 nodes, after this you may want to consider adding a Dialog instance on another host.

    Kind regards,

    Cathal

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