Messages in this thread | | | Date | Wed, 2 Dec 1998 20:04:08 -0500 (EST) | From | Jeffrey Hutzelman <> | Subject | Re: NTP dumps Linux, film at 11. [Fwd/FYI] |
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> In message <199812020115.UAA29332@dcl.MIT.EDU>, "Theodore Y. Ts'o" writes: > +----- > | Date: Tue, 01 Dec 1998 18:03:07 -0500 > | From: "Brandon S. Allbery KF8NH" <allbery@kf8nh.apk.net> > | > | The other thing about it is that it's not just lost interrupts: the > | systems are as apt to *gain* time, instead of losing it, again enough > | to make Kerberos upset (I've seen them gain 10 minutes over 5 minutes > | of wall time). Again, I haven't been able to correlate gain vs. loss > | (or amount thereof) to any particular program or device/driver. > | > | Hmm... I've never seen this myself. I've only lost time, on my clock, > | and only under very explainable circumstances (such as using the > | Bustoaster SCSI card). And I use Kerberos all the time, so I tend to > +--->8 > > It was very noticeable. I upgraded the entire cluster (14 machines) in > HH1202 one afternoon; half the machines started gaining time like mad, the > other half lost time like mad. All machines identical, indeed from the > same manufacturing batch as far as I can tell (and all idle, the spring > semester having just ended at the time). Within 15 minutes all of them > were outside of the time window the AFS kaservers were willing to grant > them (the usual 5 minutes for Kerberos) and linux-afs had lost the battle > to resync their clocks. (10 minutes later xntpd was a standard part of our > Linux install....) > > Later in the summer I upgraded them all to RH5.1, with xntpd disabled > initially so I could see how they would behave. They proceeded to do much > the same thing, except that a few of them waited most of a week before > suddenly beginning to drift wildly. > > Every (RH5-based) Linux system I've encountered, whether installed by me or > by someone else, has behaved similarly, although not always with such a > massive time slew (it varies widely and for no discernable reason, even on > the same machine). > > I've only installed 5.2 on a handful of machines so far, but the time > slippages are still there so far.
I've _never_ seen this behaviour or had users report it; perhaps there's something unusual about your installs that's making it happen, or about ours that makes it go away. We're presently using ntpd and running AFS with -nosettime, as God intended. FWIW, I'm pretty sure that Andrew uses the time-sync support in AFS on their 4.2-based workstations (as they do on every other platform), so I'm pretty sure that code works correctly.
We, of course, have the same situation as you or Ted - if our machines' time starts to fluctuate wildly, the users notice pretty quickly, because bad things happen like people not being able to log in...
-- Jeffrey T. Hutzelman (N3NHS) <jhutz+@cmu.edu> Systems Programmer School of Computer Science - Research Computing Facility Carnegie Mellon University - Pittsburgh, PA
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