Just had an odd one. Everytime I rebooted any one of my Windows VM’s, when it came back up the clock would be out by a varying amount.
VM’s on the same physical host would be out by identical amounts, but Vm’s on different physical hosts would be out by different amounts.
The physical VM host servers are all running NTPd, and are configured to sync to the pool.ntp.org server lists, so I thought this was all sorted, seems I was wrong.
Each physical box, even though it was syncing with NTP peers in the outside world, was experiencing varying degrees of skew on the clock. The amount was up to 20mins across all the physical nodes.
To correct this, I have created a cron job on each server with the following entry
0 9 * * * /usr/sbin/ntpdate -s -b -p 4 -u 0.pool.ntp.org
Now the server will correct the clock skew once each day at 9am, and hopefully now I can forget all about this :-?
