From: Joe Evans (joe.evans@kcl.ac.uk)
Date: Mon Mar 03 2003 - 10:48:29 EST
Original Message
we want to change the time setting on our main production server. Is this
safe to do with out restarting? or is it likely to confuse the system? The
machine is primarily an oracle database server (Tru64 5.0A).
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Thanks to those that replied.
There seams to be mixed opinions on this. Several people thought that going
forward in time would not be a problem. Others suggested changing the time
at single user mode.
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I believe you're ok for changing the time forward - I've had to do this
before, but there can be problems if you take the clock back - as this may
confuse anything that compares file timestamps to determine whether
something is due or not.
Lindsay Wakeman
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It's always better to take the system down to single-user mode and then
change the time. Then reboot.
Too many file date/timestamps could get confused otherwise. And the
applications that may be running that reference current date/time....
Better to change time in single-user mode.
James Eiler
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The recommendation we had from our Informix support was that it was okay to
do, but you should always restart when you have the opportunity.
We have changed the time and not rebooted and everything has been okay...
Keith Texel
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I am not a DBA but I learnt from one that you have to make sure that the
database is down before you make changes to your system time, or face a lot
of trouble. Also you must note the time at the point of change, if the
system time is 11.00am at the point you stopped it and you intend to change
the time to 10:00am. Then after the change you have to wait till it is
11.00am again before re-starting your database.
Please confirm with other DBA's but I think the above information is right,
BUT as I said earlier on I am not a Oracle person but our DBA has warned us
several times on this issue of "time".
Ebele Mba
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We do not use Oracle, but another similar DB (Ingres). I can't answer for
Oracle, but my experience with the OS is going forward in time relative to
GMT should not be a problem.
We did encounter a minor problem going backwards in time. None of the
jobs in the crontab kicked off - I guess it was waiting for the server time
to pass the most recent cron date/time activity.
So adjusting for a few seconds or minutes should be OK, anything more than
a day then you should monitor your crontab entries. The current cron
process can be killed and a new one started if cron jobs aren't picked up.
Shaun Racine
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