Time synchronization - VMS

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Thread: Time synchronization

  1. Time synchronization

    What is the most sensible way to synchronize the time in a mid-size
    OpenVMS farm today ?

    - Use NTP everywhere and forget the rest ?
    - Use DTSS with an NTP time provider ?
    - Synchronize time on internet time server ?
    - Use a radio time source ?
    - ...

    The installation I speak about is made of about 20 systems, some
    clustered, some not. Mix Alpha/Itanium. And surrounded by a much
    larger population of Unix and Windows systems.

    What are other people over here doing ?

    --
    Marc Van Dyck



  2. Re: Time synchronization

    Marc Van Dyck wrote:
    > What is the most sensible way to synchronize the time in a mid-size
    > OpenVMS farm today ?
    >
    > - Use NTP everywhere and forget the rest ?
    > - Use DTSS with an NTP time provider ?
    > - Synchronize time on internet time server ?
    > - Use a radio time source ?
    > - ...
    >
    > The installation I speak about is made of about 20 systems, some
    > clustered, some not. Mix Alpha/Itanium. And surrounded by a much
    > larger population of Unix and Windows systems.
    >
    > What are other people over here doing ?
    >


    A GREAT DEAL depends on your requirements!

    Do you want all you systems to keep UTC, correct within a millisecond or
    two? Or are you happy if they all have the SAME time even if the time
    is in error by several minutes?

    I use NTP on both my VMS and my Solaris systems. It seems to work well
    enough. On VMS it WILL bury you in log files that usually tell you
    nothing worth the disk space they occupy. You will probably want/need
    to have a weekly or monthly cleanup job.

  3. Re: Time synchronization

    Marc Van Dyck wrote:
    >
    > What is the most sensible way to synchronize the time in a mid-size
    > OpenVMS farm today ?
    >
    > - Use NTP everywhere and forget the rest ?
    > - Use DTSS with an NTP time provider ?
    > - Synchronize time on internet time server ?
    > - Use a radio time source ?
    > - ...
    >
    > The installation I speak about is made of about 20 systems, some
    > clustered, some not. Mix Alpha/Itanium. And surrounded by a much
    > larger population of Unix and Windows systems.
    >
    > What are other people over here doing ?


    We use UCX's NTP and sync up to an external source. Typically, one node
    of a cluster is a stratum 2 time source, and the others sync to it at
    stratum 3 or higher. Stand-alones are usually stratum 3.

    There's been talk internally of limiting the number of stratum 2 systems
    inside the firewall and having all the others be stratum 3 or higher. No
    positive action is imminent, AFAICT.

    David J Dachtera
    (formerly dba) DJE Systems

  4. Re: Time synchronization

    In article , Marc Van Dyck writes:
    >What is the most sensible way to synchronize the time in a mid-size
    >OpenVMS farm today ?
    >
    >- Use NTP everywhere and forget the rest ?
    >- Use DTSS with an NTP time provider ?
    >- Synchronize time on internet time server ?
    >- Use a radio time source ?
    >- ...
    >
    >The installation I speak about is made of about 20 systems, some
    >clustered, some not. Mix Alpha/Itanium. And surrounded by a much
    >larger population of Unix and Windows systems.
    >
    >What are other people over here doing ?


    Our central router uses NTP from a primary source. All other hosts use NTP to
    get the time from this router.

    Regards,
    Christoph Gartmann

    --
    Max-Planck-Institut fuer Phone : +49-761-5108-464 Fax: -452
    Immunbiologie
    Postfach 1169 Internet: gartmann@immunbio dot mpg dot de
    D-79011 Freiburg, Germany
    http://www.immunbio.mpg.de/home/menue.html

  5. Re: Time synchronization

    Marc Van Dyck writes:

    >What is the most sensible way to synchronize the time in a mid-size
    >OpenVMS farm today ?


    >- Use NTP everywhere and forget the rest ?
    >- Use DTSS with an NTP time provider ?
    >- Synchronize time on internet time server ?
    >- Use a radio time source ?
    >- ...


    >The installation I speak about is made of about 20 systems, some
    >clustered, some not. Mix Alpha/Itanium. And surrounded by a much
    >larger population of Unix and Windows systems.


    >What are other people over here doing ?


    I recently set up a cluster to use a router as an NTP time source. The
    router gets it from a radio time source. I also configured NTP for each
    node to treat the others as peers so if the time source is lost, they'll
    at least track each other.

  6. Re: Time synchronization

    In article , Marc Van Dyck writes:
    >
    > The installation I speak about is made of about 20 systems, some
    > clustered, some not. Mix Alpha/Itanium. And surrounded by a much
    > larger population of Unix and Windows systems.
    >
    > What are other people over here doing ?


    I find NTP is good enough for everything I need. Back when I
    didn't have it I did do a cluster set time via SYSMAN once
    a week because some of the nodes were slipping apart far enough
    to confuse MMS. Then I just adjusted the time when I felt like
    it, VAXen are pretty good at keeping time, especially when you get
    a lot of them together.


  7. Re: Time synchronization

    Marc Van Dyck wrote :
    > What is the most sensible way to synchronize the time in a mid-size
    > OpenVMS farm today ?
    >
    > - Use NTP everywhere and forget the rest ?
    > - Use DTSS with an NTP time provider ?
    > - Synchronize time on internet time server ?
    > - Use a radio time source ?
    > - ...
    >
    > The installation I speak about is made of about 20 systems, some
    > clustered, some not. Mix Alpha/Itanium. And surrounded by a much
    > larger population of Unix and Windows systems.
    >
    > What are other people over here doing ?


    So, as far as I can see, DTSS is an old piece of software that has
    become useless and can just be dropped ? What are its performances
    compared to NTP ? It still starts automatically with Decnet, if I
    remember well. Should/Can it be disabled, and if yes, how ?

    --
    Marc Van Dyck



  8. Re: Time synchronization

    On Apr 25, 1:00 pm, Marc Van Dyck wrote:
    > Marc Van Dyck wrote :

    [...]
    > So, as far as I can see, DTSS is an old piece of software that has
    > become useless and can just be dropped ? What are its performances
    > compared to NTP ? It still starts automatically with Decnet, if I
    > remember well. Should/Can it be disabled, and if yes, how ?


    I think that's over-stating it. At my previous employer,
    we used DTSS for all the VMS systems, but one system
    (or a pair?) served as DTSS masters and were in turn
    synchronized to NTP.

    Two points:

    1) DTSS is better at keeping all nodes closer to the
    same time (better precision?). This was the motivator
    at my previous employer where timestamps generated
    by different cluster nodes had to be correct to better
    then 0.5 secs (and were typically >0.1 secs).

    2) DTSS is more difficult to set up initially, and has a
    variety of potential gotcha's if not done correctly.
    We experienced a variety of these...

    That said, once set up, DTSS is pretty much "set it and
    forget it", especially if you want the system to do the
    time changes automatically for you.

    One final note is that the infrastructure/network people
    had is put our NTP to the nearest router as the source.
    They basically cascaded NTP throughout the network
    via the routers rather than have servers provide that
    function.

    -Ken

  9. Re: Time synchronization

    Ken.Fairfield@gmail.com used his keyboard to write :
    > On Apr 25, 1:00 pm, Marc Van Dyck wrote:
    >> Marc Van Dyck wrote :

    > [...]
    >> So, as far as I can see, DTSS is an old piece of software that has
    >> become useless and can just be dropped ? What are its performances
    >> compared to NTP ? It still starts automatically with Decnet, if I
    >> remember well. Should/Can it be disabled, and if yes, how ?

    >
    > I think that's over-stating it. At my previous employer,
    > we used DTSS for all the VMS systems, but one system
    > (or a pair?) served as DTSS masters and were in turn
    > synchronized to NTP.
    >
    > Two points:
    >
    > 1) DTSS is better at keeping all nodes closer to the
    > same time (better precision?). This was the motivator
    > at my previous employer where timestamps generated
    > by different cluster nodes had to be correct to better
    > then 0.5 secs (and were typically >0.1 secs).
    >
    > 2) DTSS is more difficult to set up initially, and has a
    > variety of potential gotcha's if not done correctly.
    > We experienced a variety of these...
    >
    > That said, once set up, DTSS is pretty much "set it and
    > forget it", especially if you want the system to do the
    > time changes automatically for you.
    >
    > One final note is that the infrastructure/network people
    > had is put our NTP to the nearest router as the source.
    > They basically cascaded NTP throughout the network
    > via the routers rather than have servers provide that
    > function.
    >
    > -Ken


    DTSS set-up, I'm used to it. That leaves only one difficulty, which
    is writing the DTSS time provider. Our network uses two utility boxes
    that get various time sources (Internet, GPS, radio) and provide NTP
    and
    SNTP time service. How do I bridge DTSS and that ? I have written in
    the past a Pascal program that acted as a DTSS time provider, using
    radio time stamps. Do I need to go this route again ?

    --
    Marc Van Dyck



  10. Re: Time synchronization

    Hi Marc,

    Marc Van Dyck wrote:

    > What is the most sensible way to synchronize the time in a mid-size
    > OpenVMS farm today ?
    >
    > - Use NTP everywhere and forget the rest ?
    > - Use DTSS with an NTP time provider ?
    > - Synchronize time on internet time server ?
    > - Use a radio time source ?
    > - ...
    >
    > The installation I speak about is made of about 20 systems, some
    > clustered, some not. Mix Alpha/Itanium. And surrounded by a much
    > larger population of Unix and Windows systems.
    >
    > What are other people over here doing ?


    With only Alpha and Itanium systems (assuming reasonably recent versions
    of OpenVMS) the advantage of DTSS (with an NTP provider or a radio time
    source, depending on your personal preferences) over NTP is small, but
    still existent.

    With DTSS, you just enable it (or don't explicitly disable it) and it
    will find its servers on the LAN (or even WAN with a bit of additional
    configuration). It also takes care about DST changes.

    With NTP, you need to define your servers and peers on every single node
    using NTP, and if someng changes, apply changes to this configuration
    again on every single node. DST changes cn be taken care of by using the
    AUTO_DLIGHT_SAV system parameter.

    So if you have the DECnet extended functions license for at least two or
    three nodes, I'd prefer DTSS and configure theses nodes as DTSS servers
    relying on NTP to get the correct time.

    If you run versions before V7.3 (or have a VAX in your environment, which
    you don't), there's no AUTO_DLIGHT_SAV parameter, so the advantage of
    DTSS over NTP is even bigger.

    Hans.

  11. Re: Time synchronization

    Marc,

    Because of the "if it ain't broken, don't fix it" theorem, we run DTSS
    on all nodes. In each datacenter, two of the nodes are configured as
    server, the rest is clerk. Also, in each datacenter, one server also
    runs the DTSS$PROVIDER_NTP as found in SYS$COMMON:
    [SYSHLP.EXAMPLES.DTSS].

    The only problem is that there is no automatic detection of ntp
    servers (although I do not know if there is such functionality in ntp
    at all). When the the network team saw it fit to replace the ntp
    servers they did not bother to tell us.

    Regards,

    Bart Zorn


    On Apr 25, 3:46 pm, Marc Van Dyck wrote:
    > What is the most sensible way to synchronize the time in a mid-size
    > OpenVMS farm today ?
    >
    > - Use NTP everywhere and forget the rest ?
    > - Use DTSS with an NTP time provider ?
    > - Synchronize time on internet time server ?
    > - Use a radio time source ?
    > - ...
    >
    > The installation I speak about is made of about 20 systems, some
    > clustered, some not. Mix Alpha/Itanium. And surrounded by a much
    > larger population of Unix and Windows systems.
    >
    > What are other people over here doing ?
    >
    > --
    > Marc Van Dyck



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