Re: [gentoo-server] UTC vs. localtime

[Benjamin Smee]

heya,

On Thu, 2005-08-11 at 12:51 +1000, Andrew Cowie wrote:
> On Tue, 2005-09-08 at 11:58 -0500, Robert Larson wrote:
> > I just recently switched a few of my servers to UTC from localtime
>
> My sense is that the responses you received in this thread, while
> helpful, sorta missed the point.

Agreed! You beat me to the post :)

> There's no reason for a server to have any system-wide timezone other
> than UTC, so yes,
>
> > /etc/conf.d/clock: CLOCK="UTC"
> > /etc/localtime -> /usr/share/zoneinfo/UTC
>
> is correct. In fact, setting the hardware clock to UTC is most correct
> for any Linux system - the only tie to mess with it is if the Linux
> installation on a machine co-exists with a broken OS, say, Windows
> perhaps.
>
> But here's the real trick: *any* individual application can localize the
> timezone information it gets by [re]setting the TZ environment variable.
> And that should be all you have to worry about.

Precisely the point. It is worth noting though that the root user should
never set anything in .bash_profile (or equivalent) to change the TZ
var, that should only be done as a user requiring the different time
view. 


On a different note, while someone mentioned the users of ntp-client and
ntpd, it is worth mentioning that openntp doesn't require the same setup
as it IS capable of making large adjustments by itself (ie no annoying
ntpdate -b before starting) and so you can just add the one init script
as supplied. In fact as general I like openntp as a replacement to ntp
BUT AFAIK it doesn't have a ntpq equivalent so its hard to know if its
actually working and how the different peers are functioning.

> [P.S. You may have to recorrect the hardware clock *once*, see `hwclock
> --help`. Also, be aware that NTP will only act if the skew is within
> certain limits, so if you're way out, it won't do anything]

Also worth noting the option:

CLOCK_SYSTOHC="yes"

in /etc/conf.d/clock. This will sync your system time to HW clock on
shutdown and is not a bad idea if you are using a NTPd system.

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