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тАО12-09-2010 08:30 AM
тАО12-09-2010 08:30 AM
We have a gang of servers that inadvertently dropped off their NTP servers (whis IP/DNS changed). All are now on average ~20 minutes ahead of actual time.
If I adjust it "online" -- with DBs, mid-tier apps and front-end apps (web tier) running -- will there be serious repercussions? Maybe dangeorus with financial systems -- right?
Solved! Go to Solution.
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тАО12-09-2010 08:48 AM
тАО12-09-2010 08:48 AM
SolutionThis will create a problem for :-
1) Authentication mechanisms on NFS
2) Incremental backups
{what i can think of off the top of my head}
If you can risk these criteria go ahead bringing time downward, however, this can cause disaster to "time sensitive" applications.
Regards
Ismail Azad
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тАО12-09-2010 08:53 AM
тАО12-09-2010 08:53 AM
Re: Effect of Correcting Time Downward on Running OS
Thanks... will check with client. I simply missed the apt terminlogy "time-sensitive"...
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тАО12-09-2010 08:53 AM
тАО12-09-2010 08:53 AM
Re: Effect of Correcting Time Downward on Running OS
Pete
Pete
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тАО12-09-2010 01:51 PM
тАО12-09-2010 01:51 PM
Re: Effect of Correcting Time Downward on Running OS
both date(1) and ntpdate(1m) offer capabilities to "slew" the clock adjustment by shortening/lengthening a second for however long it takes to get the clock back in sync (see the adjtime(2) system call)
Its all in the man pages...
HTH
Duncan
I am an HPE Employee
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тАО12-10-2010 07:33 AM
тАО12-10-2010 07:33 AM
Re: Effect of Correcting Time Downward on Running OS
The best way to fix this is to first verify that NTP is now communicating with valid servers (hint ntpq -p and /etc/ntp.conf). If not, fix that first. Then reboot the servers. HP-UX will automatically 'jump' the time and date to the value returned by the NTP server in /etc/rc.config.d/netdaemons. The alternative is to shutdown all applications on one server, then set the date manually and restart the applications. Be careful that $TZ matches your current timezone. The data command will translate what you type into the correct GMT/UTC offset. If $TZ is wrong, then the new time will be wrong.
Bill Hassell, sysadmin
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тАО12-10-2010 09:06 AM
тАО12-10-2010 09:06 AM
Re: Effect of Correcting Time Downward on Running OS
Typical NTP behaviour suggests that a drift of around 1000 seconds would cause the xntpd daemon to die and yes, 20 minutes is more than that and as bill said a reboot would do this for you because ntpdate -b would jump the time the way you would want it to.
Regards
Ismail Azad