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This will cause more UDP/NTP traffic, however, these packets are small so there should be very little or no impact over broadband links. In order to provide more accurate time, the defaults for polling frequencies and clock updates are increased which allow us to make small adjustments more frequently. Log in for work clock in and seconds still on time update#Impact of increased polling and clock update frequency RoleĬhooses best option based on Stratum of Host and Time serverįor Linux in Hyper-V, see the Allowing Linux to use Hyper-V Host Time section below. Log in for work clock in and seconds still on time windows 10#The settings for Windows Server 2016 and Windows 10 Anniversary Update (build 14393), are now unique which is why there are shown as separate columns. The following describes the changes in default configuration between Windows 2016 and previous versions for each Role. The last 3 counters cover NTP server scenarios and are helpful when determine the load and baselining your current performance. The Troubleshooting Time Accuracy and NTP section below, under Best Practices, has more detail. The first 3 counters target scenarios for troubleshooting accuracy issues. Number of requests answered by NTP Server (Responses/Sec). Number of requests received by the NTP Server (Requests/Sec). This number may be larger or smaller than the configured peers, depending on DNS resolution of peer names and current reach-ability. This is a count of active, distinct IP addresses of time servers that are responding to this client's requests. Larger or varying roundtrips can add noise to NTP time computations, which in turn may affect the accuracy of time synchronization through NTP.Īctive number of NTP Time sources being used by the NTP Client. This counter helps characterize the delays experienced by the NTP client. This is the time elapsed on the NTP client between transmitting a request to the NTP server and receiving a valid response from the server. Most recent round-trip delay experienced by the NTP Client in receiving a response from the server in microseconds. This counter helps visualize the actions being taken by W32time. The absolute clock frequency adjustment made to the local system clock by W32Time in parts per billion. Clock accuracy can be tracked using this performance counter with a low polling interval (eg:256 seconds or less) and looking for the counter value to be smaller than the desired clock accuracy limit. W32time initiates clock correction using this offset and updates the computed time in between samples with the remaining time offset that needs to be applied to the local clock. This is the actual time offset of the local clock. When a new valid sample is available, the computed time is updated with the time offset indicated by the sample. The absolute time offset between the system clock and the chosen time source, as computed by W32Time Service in microseconds. These allow you to baseline, monitor, and troubleshoot time accuracy. ![]() Performance monitor counters have been added. It was for this reason that we advised to manually disable Hyper-V Time Provider setting for machines participating in a domain in Windows 2012R2 and below. Domain joined Windows 2016 guests will find the most accurate clock, rather than defaulting to the host. The host Stratum is determined by w32time through normal means based on its source time. With the changes in Windows Server 2016, the host reports a Stratum one greater than the host Stratum, which results in better time for virtual guests. Previously the Host would present a fixed Stratum of 2, regardless of its accuracy. Load was created using prime95 benchmark using balanced profile.Īdditionally, the Stratum level that the Host reports to the guest is more transparent. For more information, see Hyper-V architecture. This improvement allows us to stay with-in 10µs of the host with an RMS, (Root Mean Squared, which indicates variance), of 50µs, even on a machine with 75% load. Improvements include more accurate initial time on VM start or VM restore and interrupt latency correction for samples provided to w32time. Windows 2016 has improved the Hyper-V TimeSync service. With these improvements we are able to achieve 1 ms accuracy with regard to UTC across a domain. ![]() Additionally, the source we use for accurate time references an improved API which gives us better resolution. Windows 2016 algorithms average out this noise using a number of different techniques which results in a stable and accurate clock. However, networks are noisy, and there can be spikes in the data from NTP due to network congestion and other factors that affect network latency. NTP uses 4 values to calculate the time offset, based on the timestamps of the client request/response and server request/response. Windows Server 2016 has improved the algorithms it uses to correct time and condition the local clock to synchronize with UTC. ![]()
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