Re: [Xen-API] XCP Guests Time Sync

[Denis Cardon <denis.cardon@xxxxxxxxxxxxxxxxxxxxxx>]

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

http://wiki.debian.org/Xen/Clocksource

> 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 :-)
Cheers,

Denis

> Thanks & cheers,
> Peter
>
>
> 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) 2.40.97.57.55
http://www.tranquil-it-systems.fr


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