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Re: [Xen-API] XCP Guests Time Sync

Hi Peter,

I found various posts on this but it is still not 100% clear to me.

I have two servers (with XCP 1.6) each running a handfull of Debian guests.

What is the best method to have the same time on all Debian guests? (On
both servers there is a PostgreSQL database running in a master <->
master replication configuration so I am interested in having everywhere
the same time).

I see the following solutions:

1) Each Debian guest has its own ntp client.
2) XCP uses ntp to sync its own time and all guests then sync themselves
with XCP.
3) ???

you can get available clocksource on your current xen kernel looking at the following /sys pseudo-file (I think in that clocksource is on a stock debian xen kernel, you may get something different if you install the xcp kernel).

cat /sys/devices/system/clocksource/clocksource0/available_clocksource

And you can get the current clocksource looking at

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

To my knowledge there is a magical clock source that is supposed to sync the dom0 and domU time in community XCP, but I was more succesfull at having independant clock and using ntp in all the domU.

You may find some more information on this page


Btw, does the installation of the "xs-tools" help in syncing times?

I don't think so, I always have to install ntp client in my domUs. Actually my nagios complains when time drift above 1 seconds, and I have 600+ XCP VMs that are in the green, so I guess this method works fine :-)



Thanks & cheers,

This body part will be downloaded on demand.

Denis Cardon
Tranquil IT Systems
Les Espaces Jules Verne, bâtiment A
12 avenue Jules Verne
44230 Saint Sébastien sur Loire
tel : +33 (0)

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