VMware ESXi host setup time (summer and autumn time changes)

[leami]

Hello,

I have a VMware ESXi host:

# vmware -vl
VMware ESXi 6.0.0 build-7967664
VMware ESXi 6.0.0 Update 3

In France, time changes every last Sunday of March 3:00 (plus one hour) and every last Sunday of October 2:00 (minus one hour).

Can you tell me how to configure this in command line for my VMware ESXi host?

As a comparison, on a Cisco device, I have the following line in my configuration:

clock summer-time CET recurring last Sun Mar 3:00 last Sun Oct 2:00

Thank you for your help and best regards.

[s_wieland]

Hello leami,

normally you don't need to configure a timezone or time changes on the ESX, because the time is UNIX time.

The correct display of the time and date information is something the UI is doing. If you set the correct time zone on your client, it will display you the correct time automatically in the vSphere or host client.

Best regards,

Sebastian

[leami]

Hello Sebastian,

Thank you for your answer.

> normally you don't need to configure a timezone or time changes on the ESX, because the time is UNIX time.

I don't understand your reasoning...

I also have "pure" Unix machines running Debian OS in my network.

And when I issue the "date" command, I get the correct date and time...

> The correct display of the time and date information is something the UI is doing.

> If you set the correct time zone on your client, it will display you the correct time automatically in the vSphere or host client.

What you say here is correct, I just checked it by connecting to the VMware ESXi host via "vSphere Client".
(I went to "Configuration -> Software -> Time configuration").

So, should I leave things as they are?

Because, on the VMware ESXi host, when I run the "date" command, I get the correct time minus one hour.

And I can't help thinking this ESXi host doesn't have the same time as the other devices in the network...

Thanks and best regards.

[flynmooney]

Time is set on the host in UTC and there is no time zone setting to change it is always UTC.  Basically you maintain the time with NTP.

Edit Time Configuration of an ESXi Host in the VMware Host Client

If you have a vCenter you then edit the timezone in vCenter

Configure the System Time Zone and Time Synchronization Settings

[Dave_the_Wave]

DST changes occur at the guest OS, not in ESXi.

All you need to do is have ESXi's ntp enabled.

The rest is done in the VM.

IMPORTANT: *disable* time sync in the VM. The VM only needs correct DST settings, ie. Microsoft releases DST patches almost monthly.

[leami]

Hello,

I think this is weird, but I have been dealing with weird configurations on various devices since the time change in France this year.

So, I guess this is just and additional weird thing among others.
And when everything looks weird to someone, I guess this someone is self-weird.

Thank you for your explanations.

Best regards.

[Dave_the_Wave]

It's not weird, and any country's changing DST is no different from other countries.

That's the whole point of UTC, you may want to read up on that.

Once ntp is enabled on your hosts, that ESXi host is now on UTC time, which is exact and independant of time zones.

It is the Guest OS that applies its correct time zone and correct DST rules to the UTC to generate "the correct clock".