VMware ESXi – How to Synchronize Time on Windows VMs Within One Second

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I'm a developer and we are using Quartz.Net, widely used scheduling library with SQL backing store to run cluster of jobs servers (VMs on ESXI cluster).

Quartz.Net requires that time will be synchronized between job server instances and recommends using NTP for it.

The clocks must be within a second of each other.

Our sysadmins using windows NTP to sync time with domain controller. Synchronization of VMs with ESXI host is off.

They keep insisting that's "within second" is not correct requirement and that cannot be met w/o hardware GPS-syncing devices. Their SLA & monitoring level are "within 3 minutes".

We are experiencing periodic (once in 2-3 months) Quartz instances out-of-sync behavior that consistent with time being out of sync.

  1. Is it correct for us to ask for "within second" or we need to ditch Quartz entirely?
  2. If yes, what changes are recommended for our setup?

Best Answer

This is 2018. Windows is capable of keeping servers synchronized within 2 ms or so, as required by MIFID II Regulations. So, your problem is a non-problem.

Our sysadmins using windows NTP to sync time with domain controller. Synchronization of VMs with ESXI host is off.

Why? The host can handle this a lot better (being hardware) and you have a lot fewer. Your sysadmins shoot themselves in the foot, then complain they are bleeding.

They keep insisting that's "within second" is not correct requirement and that cannot be met w/o hardware GPS-syncing devices. Their SLA & monitoring level are "within 3 minutes".

OLD - ancient - Windows synchronized within that timeframe because the Kerberos tickets had a 5 minute validity.

But this is, as I said, 2018. The financial industry has quite brutal requirements these days and MS has handled that for - since 2012, I think. 2016 put it fully into effect. Millisecond accuracy over the internet is a solved problem - solved 50 years ago actually, for a decent connection. NTP can handle it. You may have to put up a cheap hardware box if you want to cut down on traffic (i.e. make your own tier 3 NTP time source), but that again is not even expensive.

Is it correct for us to ask for "within second" or we need to ditch Quartz entirely?

You need to program for occasional time issues - as you would do with hardware. But "within second" is a joke of a requirement - it is trivial to meet under normal circumstances.

Some references:

https://docs.microsoft.com/en-us/windows-server/networking/windows-time-service/accurate-time

Government Regulations like: 50 ms accuracy for FINRA in the US 1 ms ESMA (MiFID II) in the EU.

Lots of detail and instructions there. This is an amazing read actually if you have to solve this problem. You may have to upgrade your hypervisor - they talk all about Hyper-V. VMWare should be able to do the same, but not sure how old your version is.

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