On Tue, 2013-01-22 at 21:16 -0600, Matt Garman wrote: > Hi, > > We have a little over 100 servers, almost all running CentOS 5.7. > Virtually all are Dell servers, generally a mix of 1950s, R610s, and > R410s. > > We use NTP and/or PTP to sync their clocks. One phenomenon we've > noticed is that (1) on reboot, the clocks are all greatly out of sync, > and (2) if the PTP or NTP process is stopped, the clocks start > drifting very quickly. > > If it was isolated to one or two servers, I'd dismiss the issue. I > also had this problem under CentOS 4. > > I suspect something is mis-configured, because I can't imagine the > hardware clock on ALL these servers is *that* bad. Well -- in my experience ( 15+ years with RH variants of Linux, and ~25 with various Unix flavors ) they CAN be that bad -- especially with some of the "economy" chipsets used with the Intel architecture. It gets worse when you have a CMOS battery that's getting old and weak. The clock may default back to its initial value, or it might just run slow. Some folks might consider this a "brute force" approach, but I keep it simple and just reset the hardware clock once a week via cron. I prefer to do it in the wee hours, shortly before the weekly cron jobs run on Sunday morning. Put something like this in root's crontab. 3 3 * * 0 /sbin/hwclock --systohc For the gory details, refer to the man page for "hwclock" and it will tell all. > > Anyone else dealt with anything similar? > > Thanks! > Matt > _______________________________________________ > CentOS mailing list > CentOS at centos.org > http://lists.centos.org/mailman/listinfo/centos -- Ron Loftin reloftin at twcny.rr.com "God, root, what is difference ?" Piter from UserFriendly