Centos Guest VM Hanging at eth0 every alternate Boot on ESXi 5.0

Description

Symptom: Every alternate reboot on Centos VM hangs on eth0. Troubleshooting: - add set -x /etc/sysconfig/network-scripts/ifup-eth to find exactly where it is hanging. - in this case it hang at arping trying to find the duplicate IP.  if ! /sbin/arping -q -c 2 -w 3 -D -I ${REALDEVICE} ${ipaddr[$idx]}

Solution

Root Cause: Arping Uses real time instead of relative time to wait for 3 seconds ,  so if real time goes back by an hour during this 3 seconds,  it will wait for 1 hour 3 seconds instead of 3 seconds. So the  root cause was time difference between Centos VM and ESXi. Workaround: - adding 2 seconds so there is no race condition between time changes. or - make sure ESXi time and Centos VM time have correct time ( in one  customer  case, they had wrong time set on Centos VM and it was off by 2 hours, even if NTP is defined in Centos VM, the time difference was too large for NTP ) - Most preferable. or - if Centos VM has to have different time than ESXi,then remove time sync via vmware tools.    vmware KB

Tags	Troubleshooting