Does a tztab change require a reboot?

[Duncan Webbe_1]

Due to the Commonwealth Games being hosted in Australia this year, our daylight saving time transition date will change from 26/03/2006 to 02/04/2006.

I realise that we need to change the tztab file to accommodate this but can anyone confirm whether we actually need to reboot our servers subsequently to affect this change properly?

[Bill Hassell · Accepted solution]

No. tztab is consulted by the time system calls immediately. You can create a test timezone in tztab that changes tonight. Then set TZ = to the test timezone name and watch that it modifies the time as required. Then modify the local timezone entry in the same way but with the correct transition date and you're set--no reboot necessary. Note that for testing, you can temporarily change the TZ value on the command line for a specific command as in:

TZ=EST5EDT date
TZ=PST8PDT date

and so on. Since you are changing the timezone rules for you current timezone value, there is no need to change /etc/TIMEZONE.

[Joseph Loo]

hi,

a reboot is require, refer to this example for the steps:

http://www1.itrc.hp.com/service/cki/docDisplay.do?docLocale=en_US&docId=200000080029538

regards.

[James R. Ferguson]

Hi Duncan:

The change per se does not require a reboot. Normally the TZ value associated with a process is derived as a process is spawned. A restart of 'cron' should handle crontasks. New session logins will obtain have their local time set according to the new rules since the TZ environmental value is set as 'login()' sources user profile file.

Otherwise, if you want to be absolutely sure that all processes use the same timezone, then reboot.

Regards!

...JRF...

[Steven E. Protter]

HP-UX based system really calculate time based on the number of seconds since Jan 1, 1970. All the tztab variable effects is the display of time.

No reboot required.

SEP

[Duncan Webbe_1]

Thank you all for your replies. It seems that while a reboot is not required, some processes (cron?) may still need to be restarted. I will use Bill's advice and test this to be sure.

I also logged a call with HP and they advised that they will be releasing a patch for this very issue mid February (I assume it simply involves replacing the tztab file). The support engineer also said no reboot would be required but seemed unsure as to whether any processes would need to be restarted.

[Peter Godron]

Duncan,
PHCO_34266 patch has been released by HP.