Date: Tue, 23 Jan 2018 08:40:51 -0700 From: Alan Somers <asomers@freebsd.org> To: Mike Pumford <michaelp@bsquare.com> Cc: FreeBSD <freebsd-stable@freebsd.org> Subject: Re: Clock occasionally jumps backwards on 11.1-RELEASE Message-ID: <CAOtMX2hNxRYR0Q3WxhM64wj5bNq2-wcOoSTxn_wixMiTQPseFA@mail.gmail.com> In-Reply-To: <0b170dae-b816-ea49-3516-40bfd1deaa2a@bsquare.com> References: <CAOtMX2iCkurg8HXn7KD9AbrPcDVSRN-jK4MR%2BgFMAd%2BOFEdpow@mail.gmail.com> <0b170dae-b816-ea49-3516-40bfd1deaa2a@bsquare.com>
next in thread | previous in thread | raw e-mail | index | archive | help
On Tue, Jan 23, 2018 at 3:48 AM, Mike Pumford <michaelp@bsquare.com> wrote: > On 22/01/2018 17:07, Alan Somers wrote: > >> Since upgrading my jail server to 11.1-RELEASE, the clock occasionally >> jumps backwards by 5-35 minutes for no apparent reason. Has anybody seen >> something like this? >> >> Details >> ===== >> >> * Happens about once a day on my jail server, and has happened at least >> once on a separate bhyve server. >> >> * The jumps almost always happen between 1 and 3 AM, but I've also seen >> them happen at 06:30 and 20:15. >> >> That's the window when the period scripts are run which if you have a > default configuration and a lot of jails will put the system under a lot of > stress. > That did not fail to escape my notice. However, none of the jails' periodic jobs involve the clock in any way. And I wouldn't think that a high CPU load could cause clock drift, could it? This isn't Windows XP, after all. > * I'm using the default ntp.conf file. >> >> Are you running ntpd inside the jail or on the jail host? On my jail > systems (which are 10.3 and 11.1) I run ntpd out the jail host (outside all > jails) and not inside the jails and the jails then get the accurate time as > the underlying host has accurate time. > Only on the host. New info: there is a possibility that my NFS server is hanging for awhile. That would explain my problem's timing. However, ntpd shouldn't be accessing any NFS shares, and I wouldn't think that a hung NFS server should be able to pause the clock. I'm doing a new experiment that should be more informative. But I'll have to wait until the problem recurs to learn anything. -Alan
Want to link to this message? Use this URL: <https://mail-archive.FreeBSD.org/cgi/mid.cgi?CAOtMX2hNxRYR0Q3WxhM64wj5bNq2-wcOoSTxn_wixMiTQPseFA>