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SAP getting time from HANA

hi , We have an ECC system with 3 app servers on windows(with correct time) and the db is on HANA which is 9 minutes ahead and it seems SAP is getting the time from HANA database which is incorrect, would anyone know why SAP is getting the time from HANA and not from its own OS .

regards

Jonu Joy

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2 Answers

  • Feb 24, 2017 at 02:44 AM

    Hi Jonu,

    Because the app servers must absolutely stay in sync with the database, and each other, they need a "single source of truth" for time. Since it is possible that the OS on each of the three could be a little bit off from each other, that's not the most reliable "single source." On the other hand, all three use the same database, so therefore using "database time" makes the most sense, and that's what the app servers are doing. Each app server can apply a different timezone offset, if necessary, but this way they will all agree with each other.

    So, your real question should be, "Why is my HANA database running 9 minutes fast?"

    Cheers,
    Matt

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    • What I'm trying to tell you is that you don't want to do that. You want the app servers to sync to the database. If they do anything else, you will end up with inconsistent database records, due to inconsistent timestamps.

      Instead, you should focus on why your database time isn't in sync with your network. Are you running HANA on-premise? Is it in time-sync with its own OS? It should be, and if that's the case, then the next logical question is why isn't the OS time for that server in sync with the rest of the servers in your network? Are they all running the same OS? I guess it's entirely possible, even likely, that they are not, since HANA has a more restrictive set of OS compatibility than the general app server (or at least it used to, when it had to be installed as an "appliance"; perhaps this isn't the case anymore), and it doesn't run on Windows (or at least it didn't in the past -- I admit I haven't checked the PAM for the latest information about this). So this would lead me to believe that the real problem is that the OS on your HANA server isn't sync'ing with the time server on your network, which would be your Active Directory domain controller.

      That means this isn't an SAP problem, or a Basis problem, per se, but a problem for your network administrators and/or server OS administrators. Are you running HANA on Linux? There must be a way to tell it to sync time with a Windows time server. If not, then the next option would be to choose a network time server that both Linux and Windows can sync to, and make sure they're both sync'ing to the same source.

      So, with this in mind, I'm going to adjust the tags on your question. This isn't an ERP, NetWeaver, or HANA question, but rather an operating system question.

  • Mar 14, 2017 at 06:17 AM

    Hi Jonu,

    SAP application servers do not get the time from the database! But every disp+work.exe will check the time of the local application server host and the database time via DBSL call on a regular basis (every ~40 minutes). If the time differs, then you get related error messages in dev_w* traces.

    Check time synchronisation of your HANA database host and the time service on Windows if they can successfully retrieve the time from your central NTP time source. This can be a Windows Domain Controller or any other NTP server.

    For Windows related time issues see SAP note 2046718.

    Best regards,

    Kalle

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