Linux guest hangs at “starting udev” (VMware vSphere)

Having recently upgraded the Virtual Infrastructure at work to vSphere, I have encountered many scenarios with CentOS 5.3 guests not booting or taking a long time to boot. The last message on the console typically indicates that it’s hanging while starting udev.

The fix for this issue is to ensure proper time keeping practices have been adhered to in accordance with the VMware Timekeeping KB.

The basic steps are:
1. Modify the kernel line of /boot/grub/grub.conf to include the following line:

clocksource=acpi_pm notsc divider=10

clocksource=acpi_pm – uses the Power Management Timer (PMTMR) available in some southbridges as primary timing source
notsc – disable the timestamp counter
divider=10 – reduces the frequency of timer interrupts by 10 (from 1000/second to 100/second)

2. Disable time sync through VMware tools (note that this will continue to happen on bootup, pause, resume, etc..):

vmware-guestd --cmd "vmx.set_option synctime 1 0"

3. Setup time sync through NTP:
a. Setup your /etc/ntp.conf to point to a good NTP server pool.
b. Set NTP to start and persist across reboots.

# yum -y install ntp
# chkconfig ntpd on
# /etc/init.d/ntpd start

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