System time changes when starting Exchange backup

[creinhard]

Hi,

I have a problem with VEEAM at a customer. When i start a backup of an Exchange VM the system time of the Exchange server changes. This is a problem because messages send during this time will get a new time stamp and therefore will not be delivered in time.

There are no errors in de eventlog on the exchange machine. The following event shows that the kernel time on the exchange machine is changed:
Log Name: System
Source: Microsoft-Windows-Kernel-General
Date: 11-5-2011 11:10:30
Event ID: 1
Task Category: None
Level: Information
Keywords: Time
User: LOCAL SERVICE
Computer: <Exchange Machine>
Description:
The system time has changed to 11-5-2011 9:10:30 from 11-5-2011 9:50:58.

This occurs as soon as the backup of the machine starts. I think it has something to do with VSS but i'm not sure. The only thing i know that a backup of an Exchange server is only alowed by using VSS. Otherwise you can get data corruption.

Does anybody experienced this issue before or knows a solution for this?

Thanks

Cor Reinhard
Senior Technical Consultant Microsoft Solutions

[Gostev]

Hi, do you possibly have time sync enabled in VMware Tools settings on this VM? If yes, you should disable that. Thanks.

[creinhard]

Found out what the problem is. For some reason during the start of this backup job the exchange server gets it's time from the ESX server which had the NTP service stopped and therefore incorrect time settings.

After i fixed the NTP client of the ESX server, the time of the ESX server was fixed. However when i started the job again the time was still changed. Even the ESX server changed it's time again although the NTP client was started the time was overruled.

The strange thing is that the time sync is not enabled. This is never recommended. So why is the time changed everytime and why is also the time changed on the ESX host even when NTP is on?

I think i'll have to check the kernel logs on the ESX host and hope to find something.

[Gostev]

I am guessing that time sync happens automatically after each snapshot operation... this makes sense, because VM gets stunned on snapshot creation and removal for a short period of time, and so the time goes out of sync.

[creinhard]

Ok i figured it out. After moving the Exchange VM to another ESX host i started the backup again and without any problems. The time did not change.

Bottom line one of the ESX hosts has problems with the time. I will have to investigate this issue.

Thanks Gostev for your answer.