| 1 | <?xml version='1.0' encoding='UTF-8'?>
|
|---|
| 2 | <!DOCTYPE topic PUBLIC "-//OASIS//DTD DITA Topic//EN" "topic.dtd">
|
|---|
| 3 | <topic xml:lang="en-us" id="changetimesync">
|
|---|
| 4 | <title>Tuning the Guest Additions Time Synchronization Parameters</title>
|
|---|
| 5 |
|
|---|
| 6 | <body>
|
|---|
| 7 | <p>The <ph conkeyref="vbox-conkeyref-phrases/product-name"/> Guest Additions ensure that the guest's system time is
|
|---|
| 8 | synchronized with the host time. There are several parameters which can be tuned. The parameters can be set for a
|
|---|
| 9 | specific VM using the following command: </p>
|
|---|
| 10 | <pre xml:space="preserve">$ VBoxManage guestproperty set <varname>VM-name</varname> "/VirtualBox/GuestAdd/VBoxService/<varname>property</varname>" <varname>value</varname>
|
|---|
| 11 | </pre>
|
|---|
| 12 | <p><varname>property</varname> is one of the following:
|
|---|
| 13 | </p>
|
|---|
| 14 | <dl>
|
|---|
| 15 | <dlentry>
|
|---|
| 16 | <dt><codeph>--timesync-interval</codeph>
|
|---|
| 17 | </dt>
|
|---|
| 18 | <dd>
|
|---|
| 19 | <p>Specifies the interval at which to synchronize the time with the host. The default is 10000 ms (10
|
|---|
| 20 | seconds). </p>
|
|---|
| 21 | </dd>
|
|---|
| 22 | </dlentry>
|
|---|
| 23 | <dlentry>
|
|---|
| 24 | <dt><codeph>--timesync-min-adjust</codeph>
|
|---|
| 25 | </dt>
|
|---|
| 26 | <dd>
|
|---|
| 27 | <p>The minimum absolute drift value measured in milliseconds to make adjustments for. The default is 1000 ms
|
|---|
| 28 | on OS/2 and 100 ms elsewhere. </p>
|
|---|
| 29 | </dd>
|
|---|
| 30 | </dlentry>
|
|---|
| 31 | <dlentry>
|
|---|
| 32 | <dt><codeph>--timesync-latency-factor</codeph>
|
|---|
| 33 | </dt>
|
|---|
| 34 | <dd>
|
|---|
| 35 | <p>The factor to multiply the time query latency with to calculate the dynamic minimum adjust time. The
|
|---|
| 36 | default is 8 times, which means as follows: </p>
|
|---|
| 37 | <p>Measure the time it takes to determine the host time, the guest has to contact the VM host service which
|
|---|
| 38 | may take some time. Multiply this value by 8 and do an adjustment only if the time difference between host
|
|---|
| 39 | and guest is bigger than this value. Do not do any time adjustment otherwise. </p>
|
|---|
| 40 | </dd>
|
|---|
| 41 | </dlentry>
|
|---|
| 42 | <dlentry>
|
|---|
| 43 | <dt><codeph>--timesync-max-latency</codeph>
|
|---|
| 44 | </dt>
|
|---|
| 45 | <dd>
|
|---|
| 46 | <p>The max host timer query latency to accept. The default is 250 ms. </p>
|
|---|
| 47 | </dd>
|
|---|
| 48 | </dlentry>
|
|---|
| 49 | <dlentry>
|
|---|
| 50 | <dt><codeph>--timesync-set-threshold</codeph>
|
|---|
| 51 | </dt>
|
|---|
| 52 | <dd>
|
|---|
| 53 | <p>The absolute drift threshold, given as milliseconds where to start setting the time instead of trying to
|
|---|
| 54 | smoothly adjust it. The default is 20 minutes. </p>
|
|---|
| 55 | </dd>
|
|---|
| 56 | </dlentry>
|
|---|
| 57 | <dlentry>
|
|---|
| 58 | <dt><codeph>--timesync-set-start</codeph>
|
|---|
| 59 | </dt>
|
|---|
| 60 | <dd>
|
|---|
| 61 | <p>Set the time when starting the time sync service. </p>
|
|---|
| 62 | </dd>
|
|---|
| 63 | </dlentry>
|
|---|
| 64 | <dlentry>
|
|---|
| 65 | <dt><codeph>--timesync-set-on-restore</codeph> 0|1
|
|---|
| 66 | </dt>
|
|---|
| 67 | <dd>
|
|---|
| 68 | <p>Set the time after the VM was restored from a saved state when passing 1 as parameter. This is the default.
|
|---|
| 69 | Disable by passing 0. In the latter case, the time will be adjusted smoothly, which can take a long time. </p>
|
|---|
| 70 | </dd>
|
|---|
| 71 | </dlentry>
|
|---|
| 72 | </dl>
|
|---|
| 73 | <p>All these parameters can be specified as command line parameters to <codeph>VBoxService</codeph> as well. </p>
|
|---|
| 74 | </body>
|
|---|
| 75 |
|
|---|
| 76 | </topic>
|
|---|
