Date: Wed, 8 Dec 2010 15:01:08 -0500 From: Dave Cundiff <syshackmin@gmail.com> To: questions@freebsd.org Subject: Terrible Clock Skew Message-ID: <AANLkTinjALniKqX2QBJ52SHVui=0uzaGsM8Tsi8r7idi@mail.gmail.com>
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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. -- Dave Cundiff System Administrator A2Hosting, Inc http://www.a2hosting.com
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