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  1. #1
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    Unanswered: DB2 DPF on AIX 5.3 - CPU usage

    Hi , One of our Test Servers has 10 CPUs. The workload is minimum on this server and how should I establish correct no of CPUs required? DB2 on the server is ver V8.2.

    For a separate project I need to install DB2 V8.2 with DPF on AIX v5.3 for a development environment ( Only for couple of developers). Are there any issues if I install DB2 with DPF on a single processor AIX server? I am not sure whether AIX servers come with a single a processor. But developers need AIX 5.3 and DB2 v8.2.

    DB2 V8.2 is out of support but unfortunately that's the current score and in the future these servers will be upgraded to V9.5 or 9.7.

    Thanks for your advice.

  2. #2
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    What matters is CPU cores, not necessarily CPU sockets (not sure which you are referring to).

    For your test server, I don't understand your question. The issue is related to how the server is licensed and whether you have to pay maintenance fees based on PVU's (which are based on CPU cores). But if you have 8.2, then maybe that is not problem since it is probably no longer under IBM maintenance contract.

    When using DPF in production, you should have a minimum of one CPU core per DPF partition (on the particular server where the DPF partition is located). It would be possible to have less than that for a development server, but maybe not a great idea.
    M. A. Feldman
    IBM Certified DBA on DB2 for Linux, UNIX, and Windows
    IBM Certified DBA on DB2 for z/OS and OS/390

  3. #3
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    Thanks for the reply. I am refering to CPU cores. Let me explain the situation.

    1)Our test server has 5 logical nodes on one physical AIX server with 10 CPUs. I was told that the license is based on CPUs and I am just wondering whether we are wasting resources here in terms of CPUs and license fee. Just try to establish how many CPUs we need for the current workload.

    In general how should I establish whether a particular DB2 server has suffice CPUs or extra CPUs that we do not require?

    2) The development server will have same 5 logical nodes, obviously on a single AIX server. Can I run it with single CPU since the workload is minimal? Or do I need 5 CPUs ?

    Thanks in advance.

  4. #4
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    You don't need a 5 CPUs. It's possible to run it with a single core. Since DB2 is multithreaded, you'll have an impact on the performance. Using 5 Nodes will make it worse.

    Have you thought about another licensing model? What about developer licenses?

  5. #5
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    Quote Originally Posted by nvk@vhv View Post
    You don't need a 5 CPUs. It's possible to run it with a single core. Since DB2 is multithreaded, you'll have an impact on the performance. Using 5 Nodes will make it worse.
    This is not what IBM recommends (or what I would recommend). Do you know anything about DPF?
    M. A. Feldman
    IBM Certified DBA on DB2 for Linux, UNIX, and Windows
    IBM Certified DBA on DB2 for z/OS and OS/390

  6. #6
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    Quote Originally Posted by stj20 View Post
    Thanks for the reply. I am refering to CPU cores. Let me explain the situation.

    1)Our test server has 5 logical nodes on one physical AIX server with 10 CPUs. I was told that the license is based on CPUs and I am just wondering whether we are wasting resources here in terms of CPUs and license fee. Just try to establish how many CPUs we need for the current workload.

    In general how should I establish whether a particular DB2 server has suffice CPUs or extra CPUs that we do not require?

    2) The development server will have same 5 logical nodes, obviously on a single AIX server. Can I run it with single CPU since the workload is minimal? Or do I need 5 CPUs ?

    Thanks in advance.
    1) As I already mentioned, in production you should have at least one CPU core for each DPF partition. Having two CPU cores per partition is often done in some environments, especially when CPU utilization is high with only one CPU core per node. It usually depends on how many simultaneous large data warehouse queries are being done at one time. Using compression (V9 or higher) also uses a lot of CPU. You should be able to monitor your CPU utilization to make this determination. However, if you already own the software (you said it is version 8.2) then I am not sure how this effects your licensing. I don't even think you can get (or pay) software maintenance on 8.2 anymore (and even if you could, it would be outrageously expensive and the terms can only change annually).

    2) You can run it on 1 CPU core, but it won't run very well. I think the minimum pricing is 2 CPU cores if you have a multi-core CPU, but as I mentioned in 1) above, I don't think you are paying for the software or the maintenance anymore so I don't understand your concern. For DPF, if you already own production license, you can purchase a developer license (one for each person who uses the system) at reduced cost, but you cannot purchase version 8.2 licenses anymore.
    M. A. Feldman
    IBM Certified DBA on DB2 for Linux, UNIX, and Windows
    IBM Certified DBA on DB2 for z/OS and OS/390

  7. #7
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    Quote Originally Posted by Marcus_A View Post
    This is not what IBM recommends (or what I would recommend). Do you know anything about DPF?
    I'm administering DPF for a couple of years now.

    Quote Originally Posted by Marcus_A View Post
    2) You can run it on 1 CPU core, but it won't run very well. I think the minimum pricing is 2 CPU cores if you have a multi-core CPU, but as I mentioned in 1) above, I don't think you are paying for the software or the maintenance anymore so I don't understand your concern. For DPF, if you already own production license, you can purchase a developer license (one for each person who uses the system) at reduced cost, but you cannot purchase version 8.2 licenses anymore.
    That's what i meant. It'll work from a technical perspectiv, but i does not make sense.
    I also recommended the developer Licenses before.

  8. #8
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    Quote Originally Posted by nvk@vhv View Post
    I'm administering DPF for a couple of years now.
    The issue with DPF is not multi-threading, but parallel processing using a separate DB2 engine (db2sysc) for each DPF partition that warrants having at least one CPU core for each DPF partition.
    Quote Originally Posted by nvk@vhv View Post
    I also recommended the developer Licenses before.
    Yes, and I added that it makes no sense since it is extremely unlikely that they are still paying for any DB2 8.2 licenses or support. I also mentioned that DB2 8.2 Developer licenses cannot be purchased anymore (withdrawn from marketing).
    Last edited by Marcus_A; 01-27-11 at 12:32.
    M. A. Feldman
    IBM Certified DBA on DB2 for Linux, UNIX, and Windows
    IBM Certified DBA on DB2 for z/OS and OS/390

  9. #9
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    Quote Originally Posted by Marcus_A View Post
    The issue with DPF is not multi-threading, but parallel processing using a separate DB2 engine (db2sysc) for each DPF partition that warrants having at least one CPU core for each DPF partition.
    Ok, my answer was unprecise. But i doesn't change a lot. Mutithreadend Processes shouldn't run on a single core. You lose the benefit from multithreading. From a technical perspective you don't need a core for a single process (My dualcore desktop PC runs 81 processes), so you can run a DPF Database on a single core.

  10. #10
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    Here is a nice picture on a high-level view on the DB2 process/thread model: The DB2 process model - IBM DB2 9.7 for Linux, UNIX, and Windows

    From the perspective of the operating system, it doesn't make much of a difference whether a new thread or a new process is to be scheduled. (You already mentioned that you run 81 processes on 2 cores = 40 processes on 1 core in avg.) You can run multi-threaded or multi-process applications on a single core, of course. For development systems, that's usually perfectly fine. For production systems, you would do some serious analysis beforehand anyway.
    Knut Stolze
    IBM DB2 Analytics Accelerator
    IBM Germany Research & Development

  11. #11
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    Quote Originally Posted by stolze View Post
    Here is a nice picture on a high-level view on the DB2 process/thread model: The DB2 process model - IBM DB2 9.7 for Linux, UNIX, and Windows

    From the perspective of the operating system, it doesn't make much of a difference whether a new thread or a new process is to be scheduled. (You already mentioned that you run 81 processes on 2 cores = 40 processes on 1 core in avg.) You can run multi-threaded or multi-process applications on a single core, of course. For development systems, that's usually perfectly fine. For production systems, you would do some serious analysis beforehand anyway.
    OP is using 8.2, which is course does not use the threaded model.

    For DPF, each partition has its own db2sysc process running, even when all the partitions are on one server. The whole purpose of DPF is to have processes running in parallel to satisfy a single SQL query. That is why the data for a given table is spread randomally across the DPF partitions using a hash alogrithm.
    M. A. Feldman
    IBM Certified DBA on DB2 for Linux, UNIX, and Windows
    IBM Certified DBA on DB2 for z/OS and OS/390

  12. #12
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    All , thanks for the advice. I have decided to go with 2 CPU cores for development server.

    Does anyone know the approach to establish CPU usage in production server ? Any tool or direction please.

  13. #13
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    On AIX, you could use nmon.

    developerWorks: Wikis - Systems - nmonanalyser

    HTH.

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