-----BEGIN PGP SIGNED MESSAGE----- Hash: SHA1 On Saturday, 2009-10-31 at 11:12 -0000, G T Smith wrote: ...
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.
The CMOS clock was not part of the original PC, it was an add-on card invented later. I think they still use the same chip, or an equivalent. And read access to it was (is?) slow, so it can not be used for timing operations.
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.
If the CMOS clock fails, the filesystem check at boot may trigger, and waste your time :-p
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 does more than that. It also adjusts (slowly) the speed of the clock, for example, and never "jumps" the time, so that processes that rely on the clock are not affected during the adjustments.
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....
But the clock is jumped, and the speed is not altered. It is not the same method. - -- Cheers, Carlos E. R. -----BEGIN PGP SIGNATURE----- Version: GnuPG v2.0.9 (GNU/Linux) iEYEARECAAYFAkrs10MACgkQtTMYHG2NR9WOWQCgkpqKBDVRb4u0BPel899Ioqus 1FQAoIHMaV70cmrrxNJjNMQEkTIaHO6X =0EQO -----END PGP SIGNATURE----- -- To unsubscribe, e-mail: opensuse+unsubscribe@opensuse.org For additional commands, e-mail: opensuse+help@opensuse.org