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Re: [Xen-users] Clock problems on Squeeze/Xen4 (clock jumps 50 minutes ahead)

On 08/27/2012 02:29 AM, Aleix Dorca Josa wrote:
> Hi all,
> My xen farm is plagued with this 'Jump 50 minutes ahead' problem. All my 
> machines run Debian Squeeze and Xen 4 in Dom0. DomU's are Squeeze too. I 
> thought this was a hardware problem but then I saw this (kind of old) 
> messages:
> http://lists.xen.org/archives/html/xen-users/2011-02/msg00609.html
> http://bugs.debian.org/cgi-bin/bugreport.cgi?bug=599161
> After reading all available info I still don't know if the bug has been 
> resolved in later builds of either the kernel or xen on Squeeze. Has anyone 
> got new information on this?
> I see that the clocksource=pit on the grub command line does not seem to fix 
> the problem. Any other hints? Change to Ubuntu server? Build my own xen 
> binary? Use Debian's backports to change the kernel version?
> This is kind of a big problem for me since the error kills ntpd on DomU's and 
> then Dovecot's processes stop themselves when time is corrected. Scripts to 
> workaround this are fine but I would rather much prefer for the clock not to 
> jump ahead.
> Thanks a lot,
> Aleix.
> _______________________________________________
> Xen-users mailing list
> Xen-users@xxxxxxxxxxxxx
> http://lists.xen.org/xen-users
We had this problem too, from what we could tell it was a hardware issue on 
some of our servers, specifically HP DL380 G5 servers, we have G6's and G7's as 
well, they don't seem to be affected.

The fix was to boot the G5 servers with clocksource=pit and cpuidle=0 on the 
xen command line. Example grub 1 entry below. Maybe the cpuidle switch is 
needed too.

title Xen-4.1.1
       root (hd0,0)
       kernel /boot/xen-4.1.1.gz dom0_mem=2048M dom0_max_vcpus=1 dom0_vcpus_pin 
clocksource=pit cpuidle=0
       module /boot/vmlinuz- ro root=/dev/cciss/c0d0p1 max_loop=32




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