I have a CentOS 6 KVM host with CentOS 6 guests, all 64bit. The host syncs time from NTP and has remained bang on.All the guests have kvm-clock listed as current_clocksource but over the last 3 weeks they have drifted by about 4 hours from the host.I was under the impression that kvm-clock would prevent this from happening. Even the RHEL docs seem to suggest this...Red Hat Enterprise Linux 5.5 and newer, and Red Hat Enterprise Linux 6.0 and newer, use kvm-clock as their default clock source. Running without kvm-clock requires special configuration, and is not recommended.Normally I would always run ntpd in guests as well as on the host to make sure the time stays in sync.Has anyone seen this happen before, know of any reasons this might have happened, and a way to prevent this from happening in the future?Ideally without having ntpd syncing from within the guests.
CentOS 6 KVM host with CentOS 6 guests kvm-clock enabled major time drift
centos;kvm;ntpd
The docs also recommend running ntpd in guests, this is absolutely normal. kvm-clock syncs the guests when they boot up, but not afterwards.