Re: [Xen-users] xen-3.2.0 problems with time (and space)

["Christopher Isip" <cmisip@xxxxxxxxx>]

On Sat, Jun 21, 2008 at 1:24 PM, [STD]Ein <ein@xxxxxxxxxxxxxx> wrote:

Have you adjusted any of the clock controls for Xen? (independent
wallclocks)
If not, there should be no reason to run ntp in your domU's.  I suspect that
ntp may actually be causing your time skews due to variations introduced by
xen's clock handling.  I would try disabling ntp in domU and see if your
clocks are still moving.

-----Original Message-----
From: xen-users-bounces@xxxxxxxxxxxxxxxxxxx
[mailto:xen-users-bounces@xxxxxxxxxxxxxxxxxxx] On Behalf Of Massimo
Mongardini
Sent: June 20, 2008 7:37 AM
To: xen-users@xxxxxxxxxxxxxxxxxxx
Subject: [Xen-users] xen-3.2.0 problems with time (and space)

Hi,
   I am experiencing some issues keeping my clock in sync in a series
of domU with xen-3.2.0.
every node is set to ntpd sync to a central server.
(server-0034 is a bare metal server and is in sync with the rest of the
world, while 35-41 are rhel4 domUs)

--------- server-0034---------
Fri Jun 20 11:49:48 GMT 2008
--------- server-0035---------
Fri Jun 20 11:50:54 GMT 2008
--------- server-0036---------
Fri Jun 20 11:49:52 GMT 2008
--------- server-0037---------
Fri Jun 20 11:49:50 GMT 2008
--------- server-0038---------
Fri Jun 20 11:49:50 GMT 2008
--------- server-0039---------
Fri Jun 20 11:50:50 GMT 2008
--------- server-0040---------
Fri Jun 20 11:50:42 GMT 2008
--------- server-0041---------
Fri Jun 20 11:49:51 GMT 2008

on the logs I see many:
Jun 20 11:54:55 server-0041 ntpd[2573]: frequency error -512 PPM exceeds
tolerance 500 PPM

Maybe as a side effect to this, the domUs timeout the connection to a
nfs server from time to time

Jun 20 09:15:38 server-0036 kernel: nfs: server fs-cluster not
responding, still trying
Jun 20 09:15:52 server-0036 kernel: nfs: server fs-cluster OK
Jun 20 09:16:35 server-0036 kernel: nfs: server fs-cluster not
responding, still trying
Jun 20 09:16:35 server-0036 kernel: nfs: server fs-cluster OK

details:
dom0: rhel4
xen: 3.2.0 compiled sources
domU: rhel4

I also have another xen environment that I use for tests with xen 3.1 on
a rhel4 dom0 and it doesn't seem to suffer for this issue:
--------- server-0002---------
Fri Jun 20 12:29:05 GMT 2008
--------- server-0012---------
Fri Jun 20 12:29:05 GMT 2008
--------- server-0040---------
Fri Jun 20 12:29:05 GMT 2008

any tip?

cheers,
Massimo

--
Massimo Mongardini
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My solution was to set clock to jiffies, disable ntp for all domU's and just run a cron job for ntpdate.  Maybe somebody else has a better solution.

Chris


 

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