Change Time on ESXi 5 Host Through vCenter or vSphere Client

[netwrkmgr]

We have two ESXi hosts and vCenter deployed. It was just discovered that the time on one of the hosts is off several minutes. How can the time be adjusted on the incorrect host? Can time on the incorrect host be set through vCenter or the vSphere client without causing issues? The servers are isoliated and not configured to use an NTP server. Many thanks in advance for any assistance.

[a_p_]

Changing the time on the hosts (no matter how) may cause issues with the guests (e.g. Kerberos). Either migrate/vMotion all VMs off this host, adjust the time and move the VMs back to it, or adjust the time in small steps (1-2 minutes) and always allow the guests to re-sync the time with their configured time source.

André

[netwrkmgr]

Thanks for the replys, it is greatly appreciated. VMware Tools on all the servers is NOT clicked to Sync time with ESXi, however, it appears that is what's happening. Which is the reason we wanted to change the host time to stop the drift (ie Windows Servers are showing their ESXi Host Time, which is perplexing). We can start moving the time a minute at a time if that would be the safest route. Any ideas on the why the hosts appear to sync with the ESXi host dispite the option being disabled? Thanks again.

[GFK]

I have seen that the host "BIOS" clock is overruling the time settings in ESXi settings. Have you checked the time setting in the host "BIOS" / UEFI?

[netwrkmgr]

Thanks for the reply. No, I havve not as we did not want to bring down the host. We have HP hosts, what whould we be checking for in BIOS besides the time?

[oasisinin]

If you have DRS enabled, can you vMotion the VMs and bring down the hosts one by one?

Is your cluster capable of handling the VM load if one host goes down for checking BIOS?

[a_p_]

Changing the host time is not related to the time synchronization settings. It's more like changing a systems BIOS time. In case you change the hosts time, the guest OS will pickup this offset and run with the wrong time until it synchronizes time with the configured time source again. I actually ran into this issue some time ago (including some virtual DCs), and I can tell you this wasn't very funny.

André

[netwrkmgr]

Sorry for the additional post, but I changed the time by one (1) minute and now the time in the vSphere client is now RED indicating that the time does not match. How can this be resolved? Many thanks again.

[oasisinin]

There shouldnt be any impact for time change unless your VMs are using ESXi clock to sync

Esxi --> Configuration --> Software --> Time configuration

Web Client:

Host -> ESXi Host -> Manage -> Settings -> Time Configuration

Hope it helps!

[netwrkmgr]

Thanks again for all the responses, they were very helpful. It appears that the sync problem may be related to the host time. If I understand the process corrrectly, when the Windows guest boots it gets it's initial time from the host and then syncs with the domain. The host gets it time from BIOS. Host 1 is correct but Host 2 is 5 mins and change fast. Since the time is more than 5 mins, the guests are not syncing and just using the initial given time. Does that make sense? So, will changing the time through the client really change the host time or is the only way to fix the time on the host through BIOS? Thanks again