Hi,
On Tue, Mar 22, 2005 at 05:37:33PM -0600, Jonathan Hutchins wrote:
On Tue, March 22, 2005 4:02 pm, Gerald Combs said:
Jonathan Hutchins wrote:
Ntp doesn't guarantee correct time, it's just another way to screw it up.
It _does_ guarantee that you have the same time as a server or a set of peers, within a given tolerance. This is helpful if you want to correlate log data on different hosts, or run "make" in an NFS-mounted directory.
That's if/when it's configured and working correctly. Then it'll even provide the correct date for your email timestamps. That's not necessarily a given though.
I had a system that, because I was relying on ntp, and because ntp was confirured correctly when I checked after setting it up, was six hours off after subsequent reboots. Gentoo had, in the absence of useful data from the DHCP server, overwritten the valid ntp config file with default garbage. (This is the default behavior for gentoo.) Caveat admin.
Six hours is like "forever" to ntpd. It doesn't like to make big changes to the system clock and will creep up to the correct time a few ms. at a time. You should call "hwclock" to set the hardware clock time to the system time when you shutdown the machine because the system time is set from the hardware clock at boot time. I can't remember if I set this up or if it was done for me by RedHat. There is also an "adjtimex" package that will keep track of the drift of your hardware clock and the last time it was set to try to set the system clock correctly. You can also go into the startup scripts for ntpd and add a call to either "rdate" or "ntpdate" to get the clock set to something reasonable.
A clock that is six hours off sounds like it could be a problem with a Linux system that likes to keep the hardware clock set to UTC and "some other OS" that likes to keep the hardware clock set to local time on a dual boot box. If this is the case you can solve the problem by using "fdisk" to change the type of the partition with "that other OS" to type 82 (linux swap).
Somewhat OT, does anybody know if the Dave Mills of ntp is the same Dave Mills that worked for Motorola in KC back around the time of the 6800/6809? -- Jim