[ovirt-users] Time synchronization in guest OS for Hosted Engine VM (for Kerberos)

[aleksey.maksimov at it-kb.ru]

Hello oVirt guru`s!

I want to configure Kerberos authentication (via MS Active Directory) for the oVirt portal.
So I need to properly configure the time synchronization for my Hosted Engine VM.
I set up chronyd service in a HE VM for time synchronization from Active Directory domain controllers:

# cat /etc/chrony.conf | grep ^[^#\;]

server 10.1.0.9 iburst
server 10.1.6.8 iburst
stratumweight 0
driftfile /var/lib/chrony/drift
rtcsync
makestep 10 3
bindcmdaddress 127.0.0.1
keyfile /etc/chrony.keys
commandkey 1
generatecommandkey
noclientlog
logchange 0.5
logdir /var/log/chrony

# chronyc tracking

Reference ID    : 10.1.0.9 (kom-dc01.holding.com)
Stratum         : 4
Ref time (UTC)  : Mon Sep 26 17:40:16 2016
System time     : 0.000437915 seconds slow of NTP time
Last offset     : -0.000789918 seconds
RMS offset      : 0.001730987 seconds
Frequency       : 13.612 ppm slow
Residual freq   : -0.009 ppm
Skew            : 0.166 ppm
Root delay      : 0.078126 seconds
Root dispersion : 0.126046 seconds
Update interval : 1031.9 seconds
Leap status     : Normal

It looks workable.

But I think that the service may conflict with the kvm-clock

# cat /sys/devices/system/clocksource/clocksource0/current_clocksource

kvm-clock

# dmesg | grep -i clock

[    0.000000] kvm-clock: Using msrs 4b564d01 and 4b564d00
[    0.000000] kvm-clock: cpu 0, msr 2:3ff84001, primary cpu clock
[    0.000000] kvm-clock: using sched offset of 6567130420 cycles
[    0.538339] kvm-clock: cpu 1, msr 2:3ff84041, secondary cpu clock
[    0.571323] acpi PNP0A03:00: _OSC: OS supports [ASPM ClockPM Segments MSI]
[    0.663452] Switching to clocksource kvm-clock
[    1.065348] rtc_cmos 00:00: setting system clock to 2016-09-25 16:16:04 UTC (1474820164)
[    1.988543] tsc: Refined TSC clocksource calibration: 3166.733 MHz
[   16.792347] Adjusting kvm-clock more than 11% (9437295 vs 9311354)

Do I need to turn off  kvm-clock in virtual machine properties? And how to do it?
Please explain the best practice.