(soft) error starting up vktm (virtual kernel timer) sounds promising. Is
that "if and only if" transaction start time is wrong.
I can't remember which functions Oracle uses time from vktm and which ones
it calls direct to the O/S, unfortunately.
Regards
Jonathan Lewis
On Tue, Sep 1, 2020 at 12:32 PM Noveljic Nenad <nenad.noveljic@xxxxxxxxxxxx>
wrote:
Jonathan,
Sayan,
Andy,
"Doesn't change" - depends on the power of 10 in the (hypothetical) error
and the amount of time Nenad watched (maybe the time stamp increases by one
second every 20 minutes, or every 200 minutes).
start_time & start_date haven't changed within 24 hours.
Anything in any of the alert logs about processes not starting up
properly, or using some specific function that doesn't get mentioned in
other alert logs?
The only startup error message is:
ORA-00800: soft external error, arguments: [Set Priority Failed], [VKTM],
[Check traces and OS configuration], [Check Oracle document and MOS notes],
[]
Incident details in:
/u00/oracle/orabase/diag/rdbms/acsi3_site1/ACSI3/incident/incdir_129660/ACSI3_vktm_9138_i129660.trc
Are any of the funny instances running on virtual machines ?
Everything is running on Solaris containers. However, only a minority ofthe databases is being affected.
I recall a case where running on vmware some processes would
intermittently record a "tim=" value in a trace file that was millions of
centiseconds wrong.
Tim in the SQL trace is correct:
..tim=11591151275421
get_t_hr0
1587367589894044
python convert_tim_to_localtime.py 11591151275421 1587367589894044
2020-09-01 13:12:21.169465
(The programs above are fromhttps://nenadnoveljic.com/blog/high-resolution-time-human-readable/)
Is there something like faketime, libfaketime, strange LD_PRELOAD?
Nothing strange.
pargs -e 24032 | grep -i fake
pargs -e 24032 | grep -i LD
envp[17]: LD_LIBRARY_PATH=/u00/oracle/orabase/product/18.7.0.0.190716_a/lib
Besides that, sysdate returns the correct value.
But thanks for the link - I didn't know about this!
Are the instances that have the problem connected by DB links?
No.
What about the others?
Some do have links some don't.
Do you have similar wrongness with scn_to_timestamp?
No.
SQL> select first_time,first_change# from v$log ;
FIRST_TIME FIRST_CHANGE#
------------------- -------------
...01.09.2020 02:12:54 12374018
SQL> select scn_to_timestamp(12374018) from dual ;
SCN_TO_TIMESTAMP(12374018)
---------------------------------------------------------------------------
01-SEP-20 02.12.54.000000000 AM
Can you replicate with a fresh instance using the same oracle home?
No
Thanks,
Nenad
https://nenadnoveljic.com/blog/
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