Windows Time service warnings: discontinuous changes in system clo

[Guest Robert Premuž]

Hi!

 

I have a problem with time synchronization on a MS Windows Server 2003 SP2.

 

In the Windows domain there are two DCs (both Windows Server 2003 SP2).

Their Windows Time Services (W32Time) are set as follows (I used

advice in

http://technet2.microsoft.com/windowsserver/en/library/a0fcd250-e5f7-41b3-b0e8-240f8236e2101033.mspx?mfr=true ):

 

The DC1 (has PDC role) synchronizes time with two NTP servers on the

Internet (zg1.ntp.carnet.hr and zg2.ntp.carnet.hr). I set this using

the following commands:

 

w32tm /config /update /manualpeerlist:"zg1.ntp.CARNet.hr,0x8

zg2.ntp.CARNet.hr,0x8" /syncfromflags:manual /reliable:yes

net stop w32time

net start w32time

w32tm /resync /rediscover

 

The DC2 synchronizes time with DC1. I set this using the following commands:

 

w32tm /config /update /syncfromflags:domhier /reliable:no

net stop w32time

net start w32time

w32tm /resync /rediscover

 

(Workstations synchronizes time with the domain, i.e. with DC1.)

 

After these settings I notice messages in the System Event Log of DC2

which show that the Time Service had to make a discontinuous change in

the system clock. This event happens approximately every 3 hours. Here

is an example of a series of events that are logged:

 

Event Type: Warning

Event Source: W32Time

Event Category: None

Event ID: 51

Date: 15.10.2007

Time: 22:40:55

Computer: DC2

Description:

Time Provider NtpClient: The time sample received from peer

DC1.foo.bar (ntp.d|192.168.1.13:123->192.168.1.11:123) differs from

the local time by 9 seconds. The observed transmission delay from the

server was 0 milliseconds.

 

Event Type: Warning

Event Source: W32Time

Event Category: None

Event ID: 50

Date: 15.10.2007

Time: 22:41:09

Computer: DC2

Description:

The time service detected a time difference of greater than 5000

milliseconds for 900 seconds. The time difference might be caused by

synchronization with low-accuracy time sources or by suboptimal

network conditions. The time service is no longer synchronized and

cannot provide the time to other clients or update the system clock.

When a valid time stamp is received from a time service provider, the

time service will correct itself.

 

Event Type: Warning

Event Source: W32Time

Event Category: None

Event ID: 51

Date: 15.10.2007

Time: 22:58:00

Computer: DC2

Description:

Time Provider NtpClient: The time sample received from peer

DC1.foo.bar (ntp.d|192.168.1.13:123->192.168.1.11:123) differs from

the local time by 12 seconds. The observed transmission delay from the

server was 15 milliseconds.

 

Event Type: Warning

Event Source: W32Time

Event Category: None

Event ID: 33

Date: 15.10.2007

Time: 22:58:25

Computer: DC2

Description:

The time service has made a discontinuous change in the system clock.

The system time has been changed by +11 seconds.

 

People that are familiar with NTP servers on Unix systems gave me the

following explanation of the problem: the hardware clock frequency on

DC2 has error (about 0,1 %) but the Windows Time service cannot take

the clock drift into account (as a NTP server on Unix). It can only

correct system time by discontinuous changes.

 

Can someone comment on this? Are there some settings for Windows Time

service that can solve this problem?

 

TIA

 

-- rpr. /Robert Premuž/