Tim Verhoeven a écrit : > On Jan 14, 2008 1:40 PM, Frederic SOULIER > <frederic.soulier at univ-tlse1.fr> wrote: > >> I'm having issue with my Centos 5.1 /Xen installation. >> I'm having 2 dom0 running 2.6.18-53.1.4.el5xen (x86_64). >> These two dom0 are connected to a SAN. >> These two dom0 hosts multiple domU like Centos 4.5 (2.6.9-55.0.9.ELxenU) >> and Centos 5.1 (2.6.18-53.1.4.el5xen). >> These two dom0 run ntpd to synchronize dom0 time. >> When i start a virtual machine on the first dom0 all seems good, the >> domU time is like the dom0 time. >> The problem appears when i migrate the domU to another dom0. >> After the migration, the time in domU on the new dom0 is totally false >> (we can have more than one day of desynchronisation) and the time on the >> domU seems to be blocked (the clock indicates always the same time ). >> In the xend Logs we can't see any error message with the debug mode. >> >> >> The solution for this moment is to restart the domU in the new dom0 to >> be synchronized again. >> We manage a lot of authentications services like CAS or Shibboleth which >> uses timestamp for security validation and this problem is very annoying >> for us. >> >> Anyone has encountered this problem ? >> Any idea how to solve it ? >> > > Hi Frederic, > > I've also seen this issue (CentOS 5.1, 64bit in Intel Xeons using > PVM). I've also found a solution to it. > > Put this in /etc/sysctl.conf : > > xen.independent_wallclock = 1 > > and then execute sysctl. > > What happens then is that the domU will do it's own timekeeping and no > longer follow the dom0. Now this also means that you need to run a > ntpd inside the domU to make sure it's clock keeps syncronised. > > That solved it for me. After migrations the clock kept running and > remained in sync. > > Regards, > Tim > > Hi Tim, Thanks for your response. Using ntp directly in my domU seems to solve my problems :-) My last question is about the source problem. Before we used Centos 5.0 with Xen in the same configuration and all was ok. The problem appears after the Centos 5.1 upgrade ( Xen was also upgraded from 3.0 to 3.1 in this release). Anyone known if this problem is local to my configuration or if it could be a bug in the new release ? Regards Fred