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  1. #1
    Join Date
    Apr 2012
    Posts
    156

    Unanswered: Latency Between App Server and DB Server

    Hello,
    This is kind of a general question but since we are having an issue and this forum has always been helpful I figured I would pose the question. Has anybody seen documentation (yes I did google already) for what is considered good network latency between an application server and database server? I found one IBM document that has less the .5ms as the recommendation. Has anyone seen "official" guidelines? I am observing what I think is high latency but need to be able to defend that 8-9 ms latency between a db server and an app server is to high. Database is DB2 V9.7.5 but this is more of a systems question.

    Thanks

  2. #2
    Join Date
    Jun 2003
    Location
    Toronto, Canada
    Posts
    5,516
    Provided Answers: 1
    I'm afraid it's like asking if a 2000 sq. ft. house is OK for your family or too small (or too big).

    If you're running 10000 tps and expect 15 ms response time from the application server then 8 ms latency is unacceptable. If you're running ETL jobs that last for hours, I'm sure you could live with that kind of latency.
    ---
    "It does not work" is not a valid problem statement.

  3. #3
    Join Date
    Apr 2012
    Posts
    156
    I understand what you are saying, just trying to come up with some general guidelines. The issue is with the individual packets being sent back in forth for a OLTP system. We are receiving 50+ms response time and I am having difficulty convincing people that this is not a db2 issue, more of an infrastructure issue.

  4. #4
    Join Date
    Jun 2003
    Location
    Toronto, Canada
    Posts
    5,516
    Provided Answers: 1
    You can use an activity event monitor to measure time spent by the database server itself. Subtract that from the application response time and you'll get an idea of how important (or unimportant) is the network latency.

    If you have budget, you can invest in the Optim Performance Manager Extended Insight, which will give you real-time information on where time is spent for each statement.
    ---
    "It does not work" is not a valid problem statement.

  5. #5
    Join Date
    Apr 2012
    Posts
    156
    Great idea, got stuck in the details of looking from the server side and not the database side. Ran a quick event monitor and some tests and we are spending 85% of our time in network latency. This should help with the documentation on where the issue is. Not much you can do on the database side when a query is 10ms, pulls 1 record (less than 8k) and takes 40 ms to return the data :-)

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