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darkbluelion-0140 avatar image
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darkbluelion-0140 asked FabioLavatelliMSFT-5217 answered

Time server when deploying disconnected ASDK

When deploying a disconnected ASDK, it is recommended install the ASDK while connected to the internet.
However for the time server IP, is it ok to use internet time server IP during deployment?

Would it be necessary for this time server to be connectable after disconnecting the ASDK from internet?
If yes, what is the workaround to connect to local time server if only one network adaptor which is connected to internet are used during deployment.

azure-stack-hub
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@darkbluelion-0140 Firstly, apologies for the delay in responding here and any inconvenience this issue may have caused. The Azure Stack ASDK deployment requires the time server be set with IP and will fail if you set it with the FQDN.

You can ping ‘time.windows.com’ and set the -TimeServer parameter with the IP returned.
NOTE: It may fail to ping but should return the IP

Ensure that Azure Stack deployment prerequisites are met.

The ASDK deployment applies the -TimeServer IP to the AzS-DC01 VM and then all the other VMs and Host sync to AzS-DC01 as the TimeServer. The TimeServer needs to be accessible to AzS-DC01in order to pass validation.
Troubleshoot the ASDK : https://docs.microsoft.com/en-us/azure-stack/asdk/asdk-troubleshooting?view=azs-2005


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Hi noted.

But just want to check that after passing validation. I would disconnect the ASDK from internet.
Would there be any issue if AzS-DC01VM could no longer access the internet time server?

Or it would just act as the time server with whatever time that was already synced beforehand?



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1 Answer

FabioLavatelliMSFT-5217 avatar image
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FabioLavatelliMSFT-5217 answered

Hi @darkbluelion-0140 ,

once your ASDK is disconnected from the Internet, AzS-DC01 VM will revert to its (virtual) CMOS clock as timesource. Get-AzSTimeSource run into a PEP session will prove that. Namely, "type", normally set to NTP for DC01 will show CMOS.

ComputerName : -DC01
DomainRole : Domain Controller
Service : Running
Type : NTP <<<< this will change to CMOS
NtpServer : . . .
. . .

I am not sure if the virtual CMOS clock is fed by the underlying host at some point. For sure it will if DC01 is rebooted. And the physical host, being part of the domain itself, will sync with DC01, so there might be a certain degree of circularity.

However, in practice, you won't notice particular disruptions but it's likely your entire Azure Stack Hub will observe a drift of its own time over time.

To prevent it from drifting you need to set a local NTP service as recommended. It can be done using Set-AzSTimeSource in your PEP session, after installation if you want to replace the initial one set during installation.
Please be aware in many cases you need to set it using ",0x8" (no quotes) if the NTP server isn't Windows.

More on Set-AzsTimeSource and the ,0x8 switch here: https://docs.microsoft.com/en-us/azure-stack/operator/azure-stack-configure-time?view=azs-2005

Best regards,
Fabio

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