From: centos-bounces@centos.org [mailto:centos-bounces@centos.org] On Behalf Of Alain Spineux
On 8/23/07, Steve Berg sberg@mississippi.com wrote:
Simon Jolle wrote:
Hi list
I always configure my systems to use our local time
(in my case
/usr/share/zoneinfo/Europe/Zurich) and disable UTC.
What are the differences between UTC and local time?
What are their
respective advantages and disadvantages?
When to use UTC?
cheers Simon
Not sure if Zurich has any sort of Daylight Savings like we do here in the US but that is one good reason to use UTC. Since our clocks shift by an hour twice a year it can make log files confusing and have other side effects. Using UTC you get a standard time that never shifts. (Except for the odd leap second every so often.) Personally I use UTC on my home system and let my shell convert it to my local time zone. For servers that I manage I always use UTC to avoid the one hour shifts of DST.
My understanding of UTC is different :-). For me the only thing changing is the time the hardware/BIOS clock maintains. At boot time the kernel read the hwclock apply the local->UTC conversion if required and work only and in any case in UTC. Then application like date, ls, syslog make conversion to localtime when printing time to the user using TZ environement variable or /etc/localtime
I think they were talking about the representation of the UTC clock under a running Linux environment rather then how it is saved in the BIOS.
It pretty much is a personal preference, I prefer local time so I don't have to do math in my head, but for most applications you can have them write their log entries in local or UTC time. Sendmail comes to mind here.
DST changes don't bother me, I know when they're going to happen so it doesn't confuse me when I look at the logs, and most log analyzers that are worth the money know when to anticipate a time shift in the logs too.
-Ross
______________________________________________________________________ This e-mail, and any attachments thereto, is intended only for use by the addressee(s) named herein and may contain legally privileged and/or confidential information. If you are not the intended recipient of this e-mail, you are hereby notified that any dissemination, distribution or copying of this e-mail, and any attachments thereto, is strictly prohibited. If you have received this e-mail in error, please immediately notify the sender and permanently delete the original and any copy or printout thereof.