Time Clock Stops in FreeBSD 9.0 guest running under ESXi 5.0

[Adam Strohl]

On 3/12/2012 0:01, Ian Lepore wrote:
 > It seems unlikely to me that ntpd and the vm tools would be fighting in
 > a way that caused this symptom.  The way ntpd affects timing is to step
 > the clock (which gets logged), or to numerically steer the kernel's
 > timekeeping routines.  The steering is clamped at 500 ppm; to make the
 > clock appear to stop it would have to steer at 1e6 ppm.  I've always
 > assumed that VM guest services daemons that handle timekeeping use the
 > same ntp_adjtime() interface to the kernel timekeeping that ntpd itself
 > uses, so the same steering limits would apply.

An excellent point.

 >
 > If it happens again, interesting data might be found in the output of:
 >
 >    sysctl kern.timecounter
 >    sysctl kern.eventtimer
 >    vmstat -i
 >    ntpdc -c kerninfo
 >    <anything unusual in dmesg output>

Will do, I know there was nothing in dmesg, I will definitely check all 
of this though if/when it happens again.  I just brought up another ESXi 
5.0 host with FreeBSD 9.0 VMs (created from dump/restore from the 
existing ones), so there is an increased chance of me seeing this 
hopefully and getting to the bottom of it.  Or it never happens again :P


On 3/19/2012 1:36, Steve Wills wrote:
> I've experienced something similar once or twice with ESXi 5.0. The
> second time it happened, I found that kern.timecounter.tc.HPET.counter
> stopped changing. I was told on IRC that this indicated a "hardware"
> problem, which I took to indicate a possible bug in ESXi. I haven't
> upgraded to ESXi 5.0 Update 1 yet to see if that changes anything.
> Rebooting of course fixed it, it has been a while since this happened
> and it hasn't happened again since so I haven't pursued it. Just another
> data point, hope it hopes.

Thanks for the info!  I didn't realize there was an update out already 
for 5.0 (I don't see it on VMWare's site).