How to keep a VMWare VM s clock in sync

Question

I have noticed that our VMWare VMs often have the incorrect time on them  No matter how many times I reset the time they keep on desyncing   Has anyone else noticed this  What do other people do to keep their VM time in sync   Edit  These are CLI linux VMs btw

User · Answer

according to VMware s knowledge base  the actual solution depends on the Linux distro and release  in RHEL 5 3  I usually edit  etc grub conf and append this parameters to the kernel entry   divider 10 clocksource acpi pm  Then enable NTP  disable VMware time synchronization from vmware-toolbox and finally reboot the VM  A complete table with guidelines for each Linux distro can be found here   TIMEKEEPING BEST PRACTICES FOR LINUX GUESTS http   kb vmware com selfservice microsites search do language en US amp cmd displayKC amp externalId 1006427

User · Answer

VMware experiences a lot of clock drift  This Google search for  vmware clock drift  links to several articles   The first hit may be the most useful for you  http   www fjc net linux linux-and-vmware-related-issues linux-2-6-kernels-and-vmware-clock-drift-issues

User · Answer

If your host time is correct  you can set the following  vmx configuration file option to enable periodic synchronization   tools syncTime   true   By default  this synchronizes the time every minute  To change the periodic rate  set the following option to the desired synch time in seconds   tools syncTime period   60   For this to work you need to have VMWare tools installed in your guest OS   See http   www vmware com pdf vmware timekeeping pdf for more information

User · Answer

VMware experiences a lot of clock drift  This Google search for  vmware clock drift  links to several articles   The first hit may be the most useful for you  http   www fjc net linux linux-and-vmware-related-issues linux-2-6-kernels-and-vmware-clock-drift-issues

User · Answer

The CPU speed varies due to power saving  I originally noticed this because VMware gave me a helpful tip on my laptop  but this page mentions the same thing   Quote from   VMWare tips and tricks Power saving  SpeedStep  C-states  P-States       Your power saving settings may interfere significantly with vmware s performance  There are several levels of power saving   CPU frequency  This should not lead to performance degradation  outside of having the obvious lower performance when running the CPU at a lower frequency  either manually of via governors like  ondemand  or  conservative    The only problem with varying the CPU speed while vmware is running is that the Windows clock will gain of lose time  To prevent this  specify your full CPU speed in kHz in  etc vmware config  host cpukHz   2167000

User · Answer

I added the following job to crontab  It is hacky but i think should work      5         service ntpd stop  amp  amp  ntpdate pool ntp org  amp  amp  service ntpd start  It stops ntpd service updates from service and starts ntpd again

User · Answer

according to VMware s knowledge base  the actual solution depends on the Linux distro and release  in RHEL 5 3  I usually edit  etc grub conf and append this parameters to the kernel entry   divider 10 clocksource acpi pm  Then enable NTP  disable VMware time synchronization from vmware-toolbox and finally reboot the VM  A complete table with guidelines for each Linux distro can be found here   TIMEKEEPING BEST PRACTICES FOR LINUX GUESTS http   kb vmware com selfservice microsites search do language en US amp cmd displayKC amp externalId 1006427

User · Answer

The CPU speed varies due to power saving  I originally noticed this because VMware gave me a helpful tip on my laptop  but this page mentions the same thing   Quote from   VMWare tips and tricks Power saving  SpeedStep  C-states  P-States       Your power saving settings may interfere significantly with vmware s performance  There are several levels of power saving   CPU frequency  This should not lead to performance degradation  outside of having the obvious lower performance when running the CPU at a lower frequency  either manually of via governors like  ondemand  or  conservative    The only problem with varying the CPU speed while vmware is running is that the Windows clock will gain of lose time  To prevent this  specify your full CPU speed in kHz in  etc vmware config  host cpukHz   2167000

User · Answer

Something to note here   We had the same issue with Windows VM s running on an ESXi host   The time sync was turned on in VMWare Tools on the guest  but the guest clocks were consistently off  by about 30 seconds  from the host clock   The ESXi host was configured to get time updates from an internal time server   It turns out we had the Internet Time setting turned on in the Windows VM s  Control Panel   Date and Time   Internet Time tab  so the guest was getting time updates from two places and the internet time was winning   We turned that off and now the guest clocks are good  getting their time exclusively from the ESXi host

User · Answer

If your host time is correct  you can set the following  vmx configuration file option to enable periodic synchronization   tools syncTime   true   By default  this synchronizes the time every minute  To change the periodic rate  set the following option to the desired synch time in seconds   tools syncTime period   60   For this to work you need to have VMWare tools installed in your guest OS   See http   www vmware com pdf vmware timekeeping pdf for more information

User · Answer

VMware experiences a lot of clock drift  This Google search for  vmware clock drift  links to several articles   The first hit may be the most useful for you  http   www fjc net linux linux-and-vmware-related-issues linux-2-6-kernels-and-vmware-clock-drift-issues

User · Answer

This documentation solved this problem for me

User · Answer

This documentation solved this problem for me

User · Answer

If your host time is correct  you can set the following  vmx configuration file option to enable periodic synchronization   tools syncTime   true   By default  this synchronizes the time every minute  To change the periodic rate  set the following option to the desired synch time in seconds   tools syncTime period   60   For this to work you need to have VMWare tools installed in your guest OS   See http   www vmware com pdf vmware timekeeping pdf for more information

User · Answer

In my case we are running VMWare Server 2 02 on Windows Server 2003 R2 Standard   The Host is also Windows Server 2003 R2 Standard   I had the VMware Tools installed and set to sync the time   I did everything imaginable that I found on various internet sites  We still had horrendous drift  although it had shrunk from 15 minutes or more down to the 3 or 4 minute range   Finally in the vmware log I found this entry  resides in the folder as the  vmx file    Your host system does not guarantee synchronized TSCs across different CPUs  so please set the  usepmtimer option in your Windows Boot ini file to ensure that timekeeping is reliable  See Microsoft KB http   support microsoft com kb    for details and Microsoft KB http   support microsoft com kb    for additional information    Cause  This problem occurs when the computer has the AMD Cool n Quiet technology  AMD dual cores  enabled in the BIOS or some Intel multi core processors  Multi core or multiprocessor systems may encounter Time Stamp Counter  TSC  drift when the time between different cores is not synchronized  The operating systems which use TSC as a timekeeping resource may experience the issue  Newer operating systems typically do not use the TSC by default if other timers are available in the system which can be used as a timekeeping source  Other available timers include the PM Timer and the High Precision Event Timer  HPET   Resolution  To resolve this problem check with the hardware vendor to see if a new driver firmware update is available to fix the issue   Note The driver installation may add the  usepmtimer switch in the Boot ini file   Once this   usepmtimer switch  was done the clock was dead on time

User · Answer

I ll answer for Windows guests   If you have VMware Tools installed  then the taskbar s notification area  near the clock  has an icon for VMware Tools   Double-click that and set your options   If you don t have VMware Tools installed  you can still set the clock s option for internet time to sync with some NTP server   If your physical machine serves the NTP protocol to your guest machines then you can get that done with host-only networking   Otherwise you ll have to let your guests sync with a genuine NTP server out on the internet  for example time windows com

User · Answer

The CPU speed varies due to power saving  I originally noticed this because VMware gave me a helpful tip on my laptop  but this page mentions the same thing   Quote from   VMWare tips and tricks Power saving  SpeedStep  C-states  P-States       Your power saving settings may interfere significantly with vmware s performance  There are several levels of power saving   CPU frequency  This should not lead to performance degradation  outside of having the obvious lower performance when running the CPU at a lower frequency  either manually of via governors like  ondemand  or  conservative    The only problem with varying the CPU speed while vmware is running is that the Windows clock will gain of lose time  To prevent this  specify your full CPU speed in kHz in  etc vmware config  host cpukHz   2167000

User · Answer

I ll answer for Windows guests   If you have VMware Tools installed  then the taskbar s notification area  near the clock  has an icon for VMware Tools   Double-click that and set your options   If you don t have VMware Tools installed  you can still set the clock s option for internet time to sync with some NTP server   If your physical machine serves the NTP protocol to your guest machines then you can get that done with host-only networking   Otherwise you ll have to let your guests sync with a genuine NTP server out on the internet  for example time windows com

User · Answer

In my case we are running VMWare Server 2 02 on Windows Server 2003 R2 Standard   The Host is also Windows Server 2003 R2 Standard   I had the VMware Tools installed and set to sync the time   I did everything imaginable that I found on various internet sites  We still had horrendous drift  although it had shrunk from 15 minutes or more down to the 3 or 4 minute range   Finally in the vmware log I found this entry  resides in the folder as the  vmx file    Your host system does not guarantee synchronized TSCs across different CPUs  so please set the  usepmtimer option in your Windows Boot ini file to ensure that timekeeping is reliable  See Microsoft KB http   support microsoft com kb    for details and Microsoft KB http   support microsoft com kb    for additional information    Cause  This problem occurs when the computer has the AMD Cool n Quiet technology  AMD dual cores  enabled in the BIOS or some Intel multi core processors  Multi core or multiprocessor systems may encounter Time Stamp Counter  TSC  drift when the time between different cores is not synchronized  The operating systems which use TSC as a timekeeping resource may experience the issue  Newer operating systems typically do not use the TSC by default if other timers are available in the system which can be used as a timekeeping source  Other available timers include the PM Timer and the High Precision Event Timer  HPET   Resolution  To resolve this problem check with the hardware vendor to see if a new driver firmware update is available to fix the issue   Note The driver installation may add the  usepmtimer switch in the Boot ini file   Once this   usepmtimer switch  was done the clock was dead on time

User · Answer

In Active Directory environment  it s important to know    All member machines synchronizes with any domain controller  In a domain  all domain controllers synchronize from the PDC Emulator  PDCe  of that domain  The PDC Emulator of a domain should synchronize with local or NTP    It s important to consider this when setting the time in vmware or configuring the time sync   Extracted from  http   www sysadmit com 2016 12 vmware-esxi-configurar-hora html

User · Answer

I ll answer for Windows guests   If you have VMware Tools installed  then the taskbar s notification area  near the clock  has an icon for VMware Tools   Double-click that and set your options   If you don t have VMware Tools installed  you can still set the clock s option for internet time to sync with some NTP server   If your physical machine serves the NTP protocol to your guest machines then you can get that done with host-only networking   Otherwise you ll have to let your guests sync with a genuine NTP server out on the internet  for example time windows com

User · Answer

When installing VMware Tools on a Windows Guest     Time Synchronisation    is not enabled by default  However        best practise    is to enable time synch on Windows Guests   There a several ways to do this from outside the VM  but I wanted to find a way to enable time sync from within the guest itself either on or after tools install   Surprisingly  this wasn   t quite as straightforward as I expected   I assumed it would be posible to set this as a parameter   config option during tools install   After a bit of searching I found a way to do this in a VMware article called    Using the VMware Tools Command-Line Interface      So  if time sync is disabled  you can enable it by running the following command line in the guest         VMwareService exe    cmd    vmx set option synctime 0 1    Additional Notes  For some  IMHO stupid  reason  this utility requires you to specify the current as well as the new value  0   disabled 1   enabled  So     if you run this command on a machine which has this already set  you will get an error saying        Invalid old value     Obviously you can    ignore    this error when run  so not a huge deal  but the current design seems a bit dumb  IMHO it would be much more sensible if you could simply specify the value you want to set and not require the current value to be specified   i e             VMwareService exe    cmd    vmx set option synctime  lt 0 1

User · Answer

I added the following job to crontab  It is hacky but i think should work      5         service ntpd stop  amp  amp  ntpdate pool ntp org  amp  amp  service ntpd start  It stops ntpd service updates from service and starts ntpd again

User · Answer

In Active Directory environment  it s important to know    All member machines synchronizes with any domain controller  In a domain  all domain controllers synchronize from the PDC Emulator  PDCe  of that domain  The PDC Emulator of a domain should synchronize with local or NTP    It s important to consider this when setting the time in vmware or configuring the time sync   Extracted from  http   www sysadmit com 2016 12 vmware-esxi-configurar-hora html

User · Answer

If your host time is correct  you can set the following  vmx configuration file option to enable periodic synchronization   tools syncTime   true   By default  this synchronizes the time every minute  To change the periodic rate  set the following option to the desired synch time in seconds   tools syncTime period   60   For this to work you need to have VMWare tools installed in your guest OS   See http   www vmware com pdf vmware timekeeping pdf for more information

User · Answer

Something to note here   We had the same issue with Windows VM s running on an ESXi host   The time sync was turned on in VMWare Tools on the guest  but the guest clocks were consistently off  by about 30 seconds  from the host clock   The ESXi host was configured to get time updates from an internal time server   It turns out we had the Internet Time setting turned on in the Windows VM s  Control Panel   Date and Time   Internet Time tab  so the guest was getting time updates from two places and the internet time was winning   We turned that off and now the guest clocks are good  getting their time exclusively from the ESXi host

User · Answer

I ll answer for Windows guests   If you have VMware Tools installed  then the taskbar s notification area  near the clock  has an icon for VMware Tools   Double-click that and set your options   If you don t have VMware Tools installed  you can still set the clock s option for internet time to sync with some NTP server   If your physical machine serves the NTP protocol to your guest machines then you can get that done with host-only networking   Otherwise you ll have to let your guests sync with a genuine NTP server out on the internet  for example time windows com

User · Answer

VMware experiences a lot of clock drift  This Google search for  vmware clock drift  links to several articles   The first hit may be the most useful for you  http   www fjc net linux linux-and-vmware-related-issues linux-2-6-kernels-and-vmware-clock-drift-issues

User · Answer

The CPU speed varies due to power saving  I originally noticed this because VMware gave me a helpful tip on my laptop  but this page mentions the same thing   Quote from   VMWare tips and tricks Power saving  SpeedStep  C-states  P-States       Your power saving settings may interfere significantly with vmware s performance  There are several levels of power saving   CPU frequency  This should not lead to performance degradation  outside of having the obvious lower performance when running the CPU at a lower frequency  either manually of via governors like  ondemand  or  conservative    The only problem with varying the CPU speed while vmware is running is that the Windows clock will gain of lose time  To prevent this  specify your full CPU speed in kHz in  etc vmware config  host cpukHz   2167000

User · Answer

When installing VMware Tools on a Windows Guest     Time Synchronisation    is not enabled by default  However        best practise    is to enable time synch on Windows Guests   There a several ways to do this from outside the VM  but I wanted to find a way to enable time sync from within the guest itself either on or after tools install   Surprisingly  this wasn   t quite as straightforward as I expected   I assumed it would be posible to set this as a parameter   config option during tools install   After a bit of searching I found a way to do this in a VMware article called    Using the VMware Tools Command-Line Interface      So  if time sync is disabled  you can enable it by running the following command line in the guest         VMwareService exe    cmd    vmx set option synctime 0 1    Additional Notes  For some  IMHO stupid  reason  this utility requires you to specify the current as well as the new value  0   disabled 1   enabled  So     if you run this command on a machine which has this already set  you will get an error saying        Invalid old value     Obviously you can    ignore    this error when run  so not a huge deal  but the current design seems a bit dumb  IMHO it would be much more sensible if you could simply specify the value you want to set and not require the current value to be specified   i e             VMwareService exe    cmd    vmx set option synctime  lt 0 1

[vmware] How to keep a VMWare VM's clock in sync?

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