topic Re: Clock Change in Operating System - HP-UX

Clock Change

AL_3001 — Fri, 28 Mar 2008 10:16:37 GMT

Hello Friends,
What all needs to be taken into consideration before the clock change. We will be stopping the sap and oracle prior to the change. Also, ntp is not running on one of the servers, how to start it. Are we required to make change to the /etc/ntp.conf file. In short, im not clear about NTP. Kindly help with your inputs. Thanks

Re: Clock Change

Dennis Handly — Fri, 28 Mar 2008 10:19:33 GMT

What clock change? Something for DST?
You don't need to do anything, it's automatic, unless you installed a new tztab patch.

Re: Clock Change

Scp_1 — Fri, 28 Mar 2008 10:23:19 GMT

If you want to change date or time, pls check for cronjobs at first with crontab -l and "at" jobs. Also ensure data integrity of files shared through NFS.

Re: Clock Change

James R. Ferguson — Fri, 28 Mar 2008 11:01:59 GMT

Hi:

NTP works in UTC (GMT). Localtime is a +- offset from UTC defined by your TZ setting. The advancing step of epoch seconds does not change. What changes is the TZ delta that is applied to the UTC time --- a smaller or larger offset as defined by the rules of your timezone and the point in the calendar at which you are.

Configuring NTP is very straightforward:

http://docs.hp.com/en/B2355-90774/ch04.html

For time sources, I urge you to see:

http://www.pool.ntp.org/

Regards!

...JRF...

Re: Clock Change

piyush mathiya — Fri, 28 Mar 2008 13:16:18 GMT

Hi Ashish,
First I just want to confirm that the impact of time modification.

1) It will effect the "make" command which is responsible to create time stamp of a new file creation or modification of file.

2) Cron will effect, if you rise up the time, i.e. current time is 9:00 and you are changing 9:00 to 9:30, cron will start all processes stimulatingly which is configured between this period. if you rise down the time, i.e. current time is 9:30 and you are changing 9:30 to 9:00 then it will wait for 30 minutes, all cron will not execute while it will reach to it's original time that menace 9:30.

3) it will effect an incremental backup, so if your data will depend on incremental backup then you have to take full backup again.

4) If you are using NFS, then also you will face some problem while creating files on client server.

Then also you want to change date and time then you can configure NTP by changing /etc/ntp.conf file.
Still you want more steps how to configure NTP or how to change date and time then give me acknowledges.

Regards,
Piyush Mathiya

Re: Clock Change

Bill Hassell — Sat, 29 Mar 2008 15:59:37 GMT

It's very important to understand that Daylight Saving never changes the system time kept by HP-UX. The current time in HP-UX is this command:

date -u

Since HP-UX (and Unix in general) is designed to handle virtually *ANY* timezone rules, there is nothing to do, certainly you do not need to change the system time. The only exception is where your local timezone is not listed in the file /usr/lib/tztab. What timezone are you in and what does this command show:

echo $TZ

Re: Clock Change

Volker Borowski — Sat, 29 Mar 2008 17:43:36 GMT

Well,

as far as SAP is concerned, there is a recomendation in a DST SAPNET-Note (#7414) to bring the system down during the switch.

So you already decided the safe way.

As far as NTP is concerned, since you do not run it, you do not need to do anything.

Make sure, that you re-login user orasid after the switch and validate the timezone (variable $TZ). Restart the oracle listener.

Make sure, that you re-login user sidadm on all applicationservers and do the same check and check the correct time in addition.
TZ and locale time reported by date should be the same on all application servers.
Then start SAP again.

Volker

Re: Clock Change

AL_3001 — Mon, 31 Mar 2008 01:04:35 GMT

Thanks for your inputs.