Ntpd and HARDWARECLOCK setting in rc.conf

Question

Hi guys!
Yesterday I installed the NTP daemon to keep my clock in sync. I followed the Arch wiki [wiki]http://wiki.archlinux.org/index.php/NTP[/wiki] and installed the ntp package. The ntp daemon is running fine but I have a question regarding the HARDWARECLOCK setting in rc.conf. According to the wiki the correct setting is something else than "UTC" or "localtime" so I set it to "ntp". Unfortunately this sets my clock 2 hours ahead (UTC + 4) of the real time every time I reboot or start my computer. The hardware clock shows the correct time though (my local time, UTC + 2). Of course the ntp daemon will adjust the time after a few minutes but it's a little annoying.  I have tried deleting /var/lib/hwclock/adjtime with no difference. If I set HARDWARECLOCK to "localtime" everything is working fine and both clocks show the same time but I don't know which consequences that may have. Do you have any advice?

Answer 1

Leonid.I wrote:
berbae wrote:So definitely the adjtime cron.hourly script is really harmless to the ntpd daemon as it doesn't even touch to the hardware clock.
Well, it would be totally pointless, if it did. In fact, the hardware clock is only needed when you start the system, in order to synchronize the kernel clock. As long as the system is running, nothing should query the hardware clock.
Actually, I don't understand what do you guys mean by "hardware clock in UTC"? I thought hwclock has no format, it is how we understand it, what matters...
Also, what is the particular advantage of using NTPD over OpenNTPD? The latter is opensource and developed by OpenBSD project, and works out of the box -- I haven't even seen the wiki about it.
the hardware clock (BIOS clock) has time in UTC or localtime - a *nix OS will use UTC by default, windows uses localtime by default, hence the reason for the setting (people who dual boot); it's not a format difference, both UTC and localtime are the same format, but localtime is local time and UTC is universal coordinated time
OpenNTPD is called Open due to the roots in OpenBSD - ntpd is of course open source too and it's the standard linux ntp daemon
ntpd is the status quo ntp service (like bind is to DNS) - it has lots of features (therefore lots of code) so it's not as light on resources as it could be and it can be confusing for some users to configure
ntpd is designed for the super precise accuracy needed by some companies or projects (tiny fractions of a second) and OpenNTPD's goal is security and low resource use; less code == more security (the security aspect is the same thing the whole OpenBSD project focuses on)
I think the main feature difference is that ntp handles drift and OpenNTPD just ignores it
Last edited by thestinger (2010-04-21 01:18:03)