Xen users - Jul 2008 - Xen guests clock is exactly 2 hours before dom0 time

Hi list,

one and hopefully last strange thing I figured out ist the systime of  
my guests.

Dom0 uses ntp for time syncronisation. I set the time on my guests  
manually but after reboot any machine (Windows server, XP, Freebsd,  
even PV Machines like ubuntu) all run local time - 2 hours.

/proc/sys/xen/independent_wallclock is set to 0 so actually the time  
should be set by dom0...(?)

Any ideas, what this could be?

Best regards

Ralf

-- 
alles bleibt anders...



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Give rtc_offset a shot.  I''m pretty sure that value is set in seconds,
so if
they''re 2 hours ahead of time, offset them by -7200.  Might want to
test
that, though.

Nathan
 


-----Original Message-----
From: "Ralf Hornik Mailings" <ralf@best.homeunix.org>
To: "Xen Users" <xen-users@lists.xensource.com>
Date: Thu, 10 Jul 2008 23:16:26 +0200
Subject: [Xen-users] Xen guests clock is exactly 2 hours before dom0 time


Hi list,

one and hopefully last strange thing I figured out ist the systime of  
my guests.

Dom0 uses ntp for time syncronisation. I set the time on my guests  
manually but after reboot any machine (Windows server, XP, Freebsd,  
even PV Machines like ubuntu) all run local time - 2 hours.

/proc/sys/xen/independent_wallclock is set to 0 so actually the time  
should be set by dom0...(?)

Any ideas, what this could be?

Best regards

Ralf

-- 
alles bleibt anders...



_______________________________________________
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http://lists.xensource.com/xen-users


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"Nathan Eisenberg" <Nathan@atlasnetworks.us> schreibte:
> Give rtc_offset a shot.
Ubuntu doesn''t seem to have kern.rtc_offset.
I set /proc/sys/xen/independent_wallclock to 1 and time on each VM seperately.

I''m just curious why the time in xen seems to be GMT while systemclock
has CEST...

Ralf
>
>
> -----Original Message-----
> From: "Ralf Hornik Mailings" <ralf@best.homeunix.org>
> To: "Xen Users" <xen-users@lists.xensource.com>
> Date: Thu, 10 Jul 2008 23:16:26 +0200
> Subject: [Xen-users] Xen guests clock is exactly 2 hours before dom0 time
>
>
> Hi list,
>
> one and hopefully last strange thing I figured out ist the systime of
> my guests.
>
> Dom0 uses ntp for time syncronisation. I set the time on my guests
> manually but after reboot any machine (Windows server, XP, Freebsd,
> even PV Machines like ubuntu) all run local time - 2 hours.
>
> /proc/sys/xen/independent_wallclock is set to 0 so actually the time
> should be set by dom0...(?)
>
> Any ideas, what this could be?
>
> Best regards
>
> Ralf
>
> --
> alles bleibt anders...
>
>
>
> _______________________________________________
> Xen-users mailing list
> Xen-users@lists.xensource.com
> http://lists.xensource.com/xen-users
>


-- 
alles bleibt anders...


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Ralf Hornik Mailings wrote:
> Dom0 uses ntp for time syncronisation. I set the time on my guests 
> manually but after reboot any machine (Windows server, XP, Freebsd, 
> even PV Machines like ubuntu) all run local time - 2 hours.
>
> /proc/sys/xen/independent_wallclock is set to 0 so actually the time 
> should be set by dom0...(?)
>
> Any ideas, what this could be?
I would guess that you''ve got the system clock set to +0200 instead of 
UTC.  Traditionally, unix has run with the system clock at UTC and all 
timestamps and so on are seconds since the 1st January 1970, 00:00:00 
UTC.  These days it''s quite possible to set the system time (the real 
time clock) to something other than UTC and the system start-up looks 
after making sure the kernel''s time is UTC.

Somewhere along the lines, I think this has broken down with your 
machine.  It looks as though system time is actually +0200 in dom0. 
I''d
start by looking closely at the output of date in dom0 -- is it CEST?

jch

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Did you run tzconfig?

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I''m curious regarding this as well, only in a different way.  For
one, I did a little search, and what I found lead me to believe that setting
/proc/sys/xen/independent_wallclock to 1 in DomUs makes them ignore the xen
clock (where 0 is default and the xen clock is used).  That said, this
presumably only applies in a paravirtual environment.  However, assuming my
understanding of this feature is correct, it wouldn''t exist in HVM
domains
because there is no /proc/sys/xen (in Linux, much less in Windows).  That
said, I got my Windows machines to display the right time by using
rtc_timeoffset, but I had to make the system clock use UTC, and therefore I
have to change the offset for DST (rtc_timeoffset=-14400 for EDT and
rtc_timeoffset=-18000 for EST).  That is a pain and I would prefer to have a
separate virtual hardware clock for each HVM DomU instead of having them
bound to whatever time Xen says it is. Does such an option exist?  If it
does, would it use some token to keep track of the DomU time vs the Dom0
time at shutdown so it could match the time passed in real life since
shutdown at next startup (create in my case, using old python scripts), or
would it still use the rtc_timeoffset, leaving me in the same boat?

-----Original Message-----
From: xen-users-bounces@lists.xensource.com
[mailto:xen-users-bounces@lists.xensource.com] On Behalf Of Ralf Hornik
Mailings
Sent: Thursday, July 10, 2008 17:16
To: Xen Users
Subject: [Xen-users] Xen guests clock is exactly 2 hours before dom0 time

Hi list,

one and hopefully last strange thing I figured out ist the systime of  
my guests.

Dom0 uses ntp for time syncronisation. I set the time on my guests  
manually but after reboot any machine (Windows server, XP, Freebsd,  
even PV Machines like ubuntu) all run local time - 2 hours.

/proc/sys/xen/independent_wallclock is set to 0 so actually the time  
should be set by dom0...(?)

Any ideas, what this could be?

Best regards

Ralf

-- 
alles bleibt anders...



_______________________________________________
Xen-users mailing list
Xen-users@lists.xensource.com
http://lists.xensource.com/xen-users



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Hi List,

"John Haxby" <john.haxby@oracle.com> wrote:
> Somewhere along the lines, I think this has broken down with your  
> machine.  It looks as though system time is actually +0200 in dom0.   
> I''d start by looking closely at the output of date in dom0 -- is
it
> CEST?
Just for information,

My Unix VM''s where not affected. The time zone was set to GMT +1  
(automatically CEST) to all servers (Dom0, and Win2k3 VM) but after  
some days the time did fall back -2 hours on Win2k3 without changing  
the current timezone. Dom0 kept its time.

My suggestion was the gplpv driver on the Windows Server that serves  
the time to the others. XP with gplpv was also affected, when I set  
the time there manually.
However booting once out of gplpv to try to reproduce it let the time  
difference dissapear, even when booting back into gplpv...Now I  
switched back to independend_wallclock -> 0

At present (for 4 days) the time did not change any more...

Regards Ralf

-- 
alles bleibt anders...


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