Mailinglist Archive: opensuse (1599 mails)

< Previous Next >
Re: [opensuse] ntp and wireless
  • From: G T Smith <grahamsmith@xxxxxxxxxxxxxxxxxxxxxxxxxxxxxx>
  • Date: Sat, 31 Oct 2009 11:12:43 +0000
  • Message-id: <4AEC1BAB.8090201@xxxxxxxxxxxxxxxxxxxxxxxxxxxxxx>
-----BEGIN PGP SIGNED MESSAGE-----
Hash: SHA1

j debert wrote:
Why do you need ntp?


Synchronising time has been a pain since the early rail services needed
to ensure that trains ran on an identifiable schedule, missing your
connection or being on one of two trains trying to use same track at the
same time would ruin anyone's day. The early British rail companies
instigated a common time across their rail networks because local times
were so variable and effectively created the first time zone to try and
eliminate this cause of such problems.

Certain network OSs and services do have operations that tend to be time
critical in a similar manner, and use the OS clock rather than the
hardware clock (which is just a simple time counter with little
additional info) for timestamping operations. The important relative
time is then the network time and status, not the local hardware clock
time, or even actual local time for that matter. Keeping the OS clock in
sync with the network time becomes more important than being in sync
with the hardware clock in this case.


Or is it so there is an excuse to neglect the system and CMOS clocks?


To be honest have not bothered much with these in years because except
in the initial boot and standalone scenario they are now largely
irrelevant in any networked environment.

see...

http://www.linuxselfhelp.com/quick/clock.html

for one take on the clock, and...

http://tldp.org/HOWTO/Clock-2.html

for something different


A script to periodically test the network connection and run netdate
or rdate when the network is up works just fine. The script can also
be run under cron at some suitably long time interval to update system
time.

Hmm... isnt this what ntpd does, occasionally check the upstream server
and initiate a resync process if things have drifted too far. Using cron
is effectively making time synchronisation process dependant on another
time related process.

It is not a particularly resource intensive daemon anyway.

ntp was created because of the need to keep system clocks accurately
synchronised on a network for some time-critical applications. Most
people do not need it. Even the author discouraged it's use.


Netdate uses ntp protocols to synchronise with a ntp server. (as does
rdate)... so....

see above


- --
==============================================================================
I have always wished that my computer would be as easy to use as my
telephone.
My wish has come true. I no longer know how to use my telephone.

Bjarne Stroustrup
==============================================================================
-----BEGIN PGP SIGNATURE-----
Version: GnuPG v2.0.9 (GNU/Linux)
Comment: Using GnuPG with SUSE - http://enigmail.mozdev.org/

iEYEARECAAYFAkrsG6sACgkQasN0sSnLmgLwvgCfcwDPxtkP747O3jdlBjpJjrY5
IlcAn0uj48TU9pzWtaBd/nVyRcbmw1Bv
=d+NN
-----END PGP SIGNATURE-----
--
To unsubscribe, e-mail: opensuse+unsubscribe@xxxxxxxxxxxx
For additional commands, e-mail: opensuse+help@xxxxxxxxxxxx

< Previous Next >
Follow Ups