Quoting Alan Altmark <[email protected]>:
On Tuesday, 11/29/2016 at 08:18 GMT, Aria Bamdad <[email protected]> wrote:
I am reaching out to the community regarding a problem that I have
observed
since SLES 9 and I wanted to reach out to see if others observe what we
do.
We run z/VM on local time (Eastern US) with the appropriate timezone. We
setup SLES 11 (SP4) via Yast -> System -> Date and time, set the correct
Region and Time Zone, and uncheck the setting that reads 'Hardware clock
set
to UTC'. This sets HWCLOCK="--localtime" in /etc/sysconfig/clock.
However,
with these settings, when Linux boots, the time is 5 hours
ahead. Up to
now, we have been correcting the system time after boot via NTP.
I recently contacted SuSE support and for the past week, we have been
trying
to figure out why this is to no avail. We also tried
using a kernel
boot
parameter clocksource=tod in conjunction with setting the option for
"Hardware clock set to UTC" as checked. This seems to correct the time
but
clearly is not the correct settings.
Would anyone care to provide some input with respect to this? Do you
observe this behavior with z/VM running on local time and if so, what
do
you see with respect to Linux time at boot?
It sounds like the Linux TZ variable is not set, giving you an offset of 0
from UTC. The virtual TOD is on UTC because your machine is
nominally set
to "UTC" (which is technically incorrect for z Systems).
Also, please be aware of
http://www.vm.ibm.com/devpages/altmarka/vmleap.html.
Alan Altmark
Alan, thanks for your reply. I am afraid I don't quite understand. You are
correct that the TZ variable is not set when I login but even when I set it
correctly, the time is still the same as before. However, the time is
incorrect
even early on in the boot process.
When you say the virtual TOD is on UTC, do you mean that even if I IPL
z/VM using
the local time and timezone, the TOD reported to Linux is in UTC?
Then this means
regardless of what z/VM time is set to, the guests always see UTC as
the TOD time.
Based on the above, I tested setting the correct region, and then
selected 'Hardware
clock set to UTC' in Yast and rebooted. Sure enough, the time in
Linux shows my local
time correctly.
So does this mean that regardless of what z/VM time is set to, the
Linux guests should
select their time as 'Hardware clock set to UTC'?
Is the kernel parameter clocksource=tod needed?
Thanks,
Aria
----------------------------------------------------------------------
For LINUX-390 subscribe / signoff / archive access instructions,
send email to [email protected] with the message: INFO LINUX-390 or visit
http://www.marist.edu/htbin/wlvindex?LINUX-390
----------------------------------------------------------------------
For more information on Linux on System z, visit
http://wiki.linuxvm.org/
