effects of changing time and/or timezone on ESXi hosts

[vadm168]

Hi,

I inherited a VMware environment and notice several ESXi hosts' time is not sync'd. In fact, some are so off that I am concerned. I know VMs have a setting that can enable sync'ing VM's time with ESXi's. Also I suppose ESXi's own logs use this time setting to specify time of events. My questions are:

* Are there other things I need to worry about before configuring NTP on the ESXi hosts to ensure it's always sync'd?

* What are the potential issues if I change timezone of the ESXi hosts? In fact, I am unclear about the best practices on setting time zones. I have several ESXi hosts across US and Europe and I personally prefer setting to the ESXi hosts' local time zones so troubleshooting from the logs is easier.

Thank you.

[Wonlliv · Accepted solution]

Hi,

I had a site bookmarked which should answer you questions 🙂

Best Practices for Time Sync

Snip:

Guest time sync

For achieving accurate timekeeping in guest operating systems, there are two main issues to consider: correctly configuring time synchronization and avoiding excessive CPU and memory overcommitment. Time synchronization utilities are necessary to correct time drift introduced by hardware time drift and guest operating system timekeeping imprecision. Excessive overcommitment can cause timekeeping drift at rates that are uncorrectable by time synchronization utilities.

http://kb.vmware.com/kb/1318 - Timekeeping best practices for Windows

http://kb.vmware.com/kb/1006427 - Timekeeping best practices for Linux guests

Windows w32time vs. VMware tools NTP -- Which one?

http://www.vladan.fr/time-keeping-for-windows-vms-best-practices/

http://www.vmware.com/pdf/vmware_timekeeping.pdf

http://www.vmware.com/files/pdf/Virtualizing_Windows_Active_Directory.pdf

[Finikiez]

Hi!

ESXi doesn't use timezone setting. ESXi uses UTC timezone for logs and etc.

You configure NTP settings to have synced time across components and this helps to show proper time for tasks and events in web client.

ESXi logs are also written with UTC timestamps. To properly read them you need to manually calculate the time according to timezone you need.