Can i control the NTP Sync? - NTP

This is a discussion on Can i control the NTP Sync? - NTP ; Dear Experts, I am thinking of using the NTP services, but I have one problem which is When the time zone change from summer to winter or from winter to summer So currently we have control on the local time ...

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Thread: Can i control the NTP Sync?

  1. Can i control the NTP Sync?

    Dear Experts,
    I am thinking of using the NTP services, but I have one problem which is
    When the time zone change from summer to winter or from winter to summer
    So currently we have control on the local time and we changed manually when the time zone change, because we dont change the local time on that machine even due the time zone changed if we have a running operation and we keep it this way until the ongoing job
    Finish. So the problem here if we have the NTP server sync to that machine the sync will force the local time to change, which will affect our operation.

    Any suggestion

    Regards,
    Sami
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  2. Re: Can i control the NTP Sync?

    On 2008-08-11, Sami al flaish wrote:

    > I am thinking of using the NTP services, but I have one problem which
    > is When the time zone change from summer to winter or from winter
    > to summer So currently we have control on the local time and we
    > changed manually when the time zone change, because we don't change
    > the local time on that machine even due the time zone changed if we
    > have a running operation and we keep it this way until the ongoing
    > job Finish. So the problem here if we have the NTP server sync to
    > that machine the sync will force the local time to change, which will
    > affect our operation.


    NTP synchronizes computer clocks to a common time base. In practice this
    time base is UTC.

    UTC is independent of winter/summer time zone changes.

    Your OS is responsible for handling the winter/summer time zone changes.

    --
    Steve Kostecke
    NTP Public Services Project - http://support.ntp.org/

  3. Re: Can i control the NTP Sync?

    sflaish@hotmail.com (Sami al flaish) writes:

    >Dear Experts,
    >I am thinking of using the NTP services, but I have one problem which is
    >When the time zone change from summer to winter or from winter to summer
    >So currently we have control on the local time and we changed manually when the time zone change, because we dont change the local time on that machine even due the time zone changed if we have a running operation and we keep it this way until the ongoing job
    >Finish. So the problem here if we have the NTP server sync to that machine the sync will force the local time to change, which will affect our operation.


    ntp knows nothing about time zones. It gets the remote time in UTC. time
    zone info is all handled by your local machine. On unix/linux/.. (sensible
    machnes) the machine time is ALWAYS UTC. time routines do the translation
    using a file called /etc/localtime. On windows it is more difficult, since
    Microsoft has never heard of timezones, so you have to kludge it yourself.
    Exactly how your machine or your implimentation of ntp kludges it I do not
    know.



  4. Re: Can i control the NTP Sync?

    Unruh wrote:
    []
    > ntp knows nothing about time zones. It gets the remote time in UTC.
    > time zone info is all handled by your local machine. On unix/linux/..
    > (sensible machnes) the machine time is ALWAYS UTC. time routines do
    > the translation using a file called /etc/localtime. On windows it is
    > more difficult, since Microsoft has never heard of timezones, so you
    > have to kludge it yourself. Exactly how your machine or your
    > implimentation of ntp kludges it I do not know.


    No, you do not need to "kludge it yourself" with Windows - there is a set
    of routines built into Windows you can call if you wish to get local time,
    and a set of registry values provided and updated with Windows which allow
    it to keep local time in just the same way as other systems. If you have
    to intervene manually you are doing something wrong. Windows, like many
    modern OSes, works in UTC internally.

    David



  5. Re: Can i control the NTP Sync?

    Unruh wrote:

    > machnes) the machine time is ALWAYS UTC. time routines do the translation
    > using a file called /etc/localtime. On windows it is more difficult, since


    Not all Unixes use the Olson package and some may use a different
    location for this file. Some Unixes, in current use, encode the rules
    in an environment variable, which needs to be changed when the rules
    change (but not when the clocks change), and thus an application
    restart. Earlier ones only allowed the base timezone offset to be
    changed but had the, historic, US timezone rules hardcoded. I think the
    original Unix did timezones only the kernel.

    You will have some problems in exchanging media between Unix systems if
    you don't run them on UTC, as file timestamps are stored in the POSIX
    encoding of UTC and converted to local time by the ls command, etc.

    > Microsoft has never heard of timezones, so you have to kludge it yourself.


    Microsoft have supported timezones since Windows 9x or earlier and have
    reasonably proper support since Windows NT. For legacy reasons, they
    store wall clock time in the RTC hardware. Windows encodes the rules in
    the registry and the registry needs updating when the rules change, but
    I don't think you need an application restart. (Both the older Unix
    system and NT are limited to two changes and two offsets per year.)

    > Exactly how your machine or your implimentation of ntp kludges it I do not
    > know.


    More precisely, you always need to specify what OS you are using. Not
    specifying in an NTP context tends to imply Linux, but Linux tends to be
    leading edge and any recent one will use the Olson package.

  6. Re: Can i control the NTP Sync?

    David J Taylor wrote:

    > it to keep local time in just the same way as other systems. If you have
    > to intervene manually you are doing something wrong. Windows, like many
    > modern OSes, works in UTC internally.


    Using UTC internally is, I think, only true of NT, and comes from its
    VMS heritage, rather than from its Windows one. I seem to remember that
    Windows 3.x was not timezone aware, and I think that Windows 9.x only
    has per system timezone information and works internally on local time.
    (Quite a few home users still use Windows 95 and some small businesses
    probably still do so - it might also be in embedded systems used by
    larger businesses.)

    FAT and VFAT filesystems always use local time. I'm not sure about NTFS.

    Windows timezone handling is limited to a single pair of rules per
    timezone, with one (or zero) changes each way between two offsets. The
    Olson package, used on most Linuxes and modern Unixes, can record all
    historic and all future changes, even if they are not reducible to one,
    simple, rule.

    Whilst you can force, at least some, NT systems to treat the RTC as UTC,
    most system administrators don't even know this.

  7. Re: Can i control the NTP Sync?

    David Woolley wrote:
    > David J Taylor wrote:
    >
    >> it to keep local time in just the same way as other systems. If you
    >> have to intervene manually you are doing something wrong. Windows,
    >> like many modern OSes, works in UTC internally.

    >
    > Using UTC internally is, I think, only true of NT, and comes from its
    > VMS heritage, rather than from its Windows one.


    Well, since 1992! NT 3.1, 3.5, 4, Windows 2000, XP , Vista etc!

    I'm not talking 16-bit Windows or DOS.

    > I seem to remember
    > that Windows 3.x was not timezone aware, and I think that Windows 9.x
    > only has per system timezone information and works internally on
    > local time. (Quite a few home users still use Windows 95 and some
    > small businesses probably still do so - it might also be in embedded
    > systems used by larger businesses.)


    32-bit Windows such as 95/98/ME etc. all support the same time API, and
    use UTC internally.

    > FAT and VFAT filesystems always use local time. I'm not sure about
    > NTFS.


    NTFS and CDFS (I think) use UTC. Windows remains compatible when access
    the older file systes, as I hope would UNIX and its derivatives.

    > Windows timezone handling is limited to a single pair of rules per
    > timezone, with one (or zero) changes each way between two offsets. The
    > Olson package, used on most Linuxes and modern Unixes, can record
    > all historic and all future changes, even if they are not reducible
    > to one, simple, rule.
    >
    > Whilst you can force, at least some, NT systems to treat the RTC as
    > UTC, most system administrators don't even know this.


    It would be useful to have a record of leap seconds as well. Is that in
    the Olson package?

    For my own stuff - photos mainly - I stick with labelling in UTC time - no
    offsets at all. My wife prefers local time in the country taken. So her
    and my photos in Australia have names which are 11 hours (IIRC) different:

    2008-08-13-0100-1234.jpg
    2008-08-13-1200-1234.jpg

    Can be fun when you are looking at photos from three different cameras
    taking multiple shots of the same subject (a group of friends on the
    Sydney Harbour bridge walk), all on (sigh) slightly different time
    settings (even though precisely synched before leaving home).

    Cheers,
    David



  8. Re: Can i control the NTP Sync?

    "David Woolley" wrote in message
    news:48a28a86$0$632$5a6aecb4@news.aaisp.net.uk...
    [...]
    > Using UTC internally is, I think, only true of NT, ...


    Which, conveniently, is also the only Windows family that will run NTP.

    Groetjes,
    Maarten Wiltink



  9. Re: Can i control the NTP Sync?

    Sami al flaish wrote:
    > Dear Experts,
    > I am thinking of using the NTP services, but I have one problem which is
    > When the time zone change from summer to winter or from winter to summer
    > So currently we have control on the local time and we changed manually when the time zone change, because we dont change the local time on that machine even due the time zone changed if we have a running operation and we keep it this way until the ongoing job
    > Finish. So the problem here if we have the NTP server sync to that machine the sync will force the local time to change, which will affect our operation.
    >
    > Any suggestion


    NTP does NOT keep local time. It keeps Universal Time Coordinated (UTC).

    Shifts in local time due to summer/winter do not affect the current time
    in UTC or NTPD! If your system is configured with the correct time
    zone for your locality, and if your system has the proper data as to
    WHEN the changes to and from daylight time occur, everything should work.

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