Date change causes 100% utilization with novell-xsrvd

  • 3374649
  • 12-Dec-2007
  • 27-Apr-2012

Environment

Novell ZENworks Desktop Management 7 - ZDM7 PreBoot Services (PXE)
Novell Open Enterprise Server (Linux based)

Situation

If the date shows Thu Aug 10 09:47:12 MDT 2006, then change the date to any other date say one minute before with this commanddate 0810094606
NTP changing the date back in time causes 100% utilization with novell-xsrvd.

Resolution

Sync NDS replicas to a hardware box instead of a Virtual Machine box

Additional Information

Root Cause: Syncing DS replicas to a master Virtual Machine box was causing the time to drift in the future and constantly be reset back in time.
The problem occurs more readily on VMs because of the well-known issues keeping clocks synced in a VM environment. Using kernel parameters such as clock=pit is enough to keep the clock stable enough for xntpd to keep it in line, but it will likely still have to make stepwise adjustments occasionally. Normally, NTP will keep the clock in sync by "slewing" it - slowing it down or speeding up as needed, but if the time difference is"large" (greater than 128ms by default), NTP will step the clock. It was found that ntp on some VMs was doing this often enough, and consequently causing XTier to flip out when doing a stepwise adjustment backwards.
Fortunately, you can force NTP to always adjust the time by slewing and never by stepping the clock. To do so, add to ntp.conf:
tinker step 0
which specifies the clock difference in ms before NTP should apply a step instead of slewing. Setting to 0 disables step adjustments entirely.

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