ntp question

[Ferdie Castro]

I need have 3 HP (A, B and C) boxes and are sync in time. Applications are currently running in this boxes- oracle & stuffs. I have a time problem--its advanced 3 hrs. All of thise boxes are sync using ntp.
How do I decrease the time by 3hrs without any downtime. example time today is 1am but server time upon date command its 4am.

[RAC_1]

If I understand your question correctly
the servers(A,B,C) are all using ntp.

And the time is 3 hhrs ahead.

As you are running database/apps on the servers, it wont be good to adjust the time on the fly.

Instead you can do this when you get database/apps downtime, stop ntp on all servers. Adjust time on all servers and start ntp. (This will synchronise all servers)

Adjusting it on main ntp servers and then starting ntp on others will create the problem for other servers as the offset wud be too high to adjust.

[Ferdie Castro]

Hi RAC, thanks for your reply but what do you mean "offset would be high to adjust" if modification will be done on ntp server.
Also we can't easily down the server since the application has written to database in advance. There could a a possibility for oracle to crash since it was able to write in the database during that time.

[RAC_1]

If I understood your question correctly, servers ABC are running ntp. (one of them acting as main servers, say A. Servers Band C point to A fot ntp)

If you adjust the time on main server i.e. server A, then there will be big time difference between time on server A and servers B,C.

If this differenece is high B and C will error out while adjusting their time to that of server A

[Elmar P. Kolkman]

I have seen this at our site for even more then 3 hours. A good way is using ntpdate with the '-B' option, meaning it will change the speed at which the internal clock is used, resulting in slowly going to the right speed. This will take some time, but is the best way for your databases. Unless the database contains date records, which are used for calculations, because they will be meaningless for the period the clock is getting right. But then, the clock is not correct now either.

Hope this helps in solving your problem.