Date: Wed, 8 Dec 2010 22:22:51 -0700 From: Modulok <modulok@gmail.com> To: Dave Cundiff <syshackmin@gmail.com> Cc: questions@freebsd.org Subject: Re: Terrible Clock Skew Message-ID: <AANLkTik3kiFWG8-6DztfVUkov6pH=D7xS8RBAynVFez4@mail.gmail.com> In-Reply-To: <AANLkTinjALniKqX2QBJ52SHVui=0uzaGsM8Tsi8r7idi@mail.gmail.com> References: <AANLkTinjALniKqX2QBJ52SHVui=0uzaGsM8Tsi8r7idi@mail.gmail.com>
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On 12/8/10, Dave Cundiff <syshackmin@gmail.com> wrote: > Hi everyone, > > I posted this to the forum as well but figured I'd try here since the > same people might not subscribe to both. > > I've been experiencing some terrible clock skew and just can't figure > it out. By terrible I mean I'm losing 30 minutes a day. The loss only > occurs when I bring the system under heavy load. The load is multiple > Rsync backups to a ZFS pool(with gzip compression) backed by a 16 disk > Raid50. I'm using a hardware Raid controller for battery backed write > caching. > > Mobo: Supermicro X8DTL > CPU: Dual Intel 5620 quad cores > Raid: Areca 1620 > > I have ntp enabled but the skew happens to fast and it stops trying. > I've tried a bunch of stuff from the various lists. I tried all my > clock sources. TSC(-100) HPET(900) ACPI-fast(1000) i8254(0). I tried > changing the kern.hz flag lower. I also tried disabling the enhanced > speed step feature of this chip as per the FAQ on the site. Nothing > works. > > Currently I'm defaults except the following settings. > > EIST Disabled in BIOS > kern.hz="100" > kern.timecounter.hardware=i8254 > > Is there anything else I could do to debug this? I can't really blame > the hardware because I have these same boards/chips running in Linux > with no clock issues. In the man page for ntpd, you might look into "The huff-n'-puff Filter". Not saying it will help, but it seems like you've tried everything else. -Modulok-
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