Top 5 Do’s for VMware

I’ve put together a quick list of the Top 5 Do’s and Don’ts for VMware which I hope you’ll find useful.

Today I’m starting with the Top 5 Do’s

DO

1)   Select the correct operating system when creating your Virtual Machine.  Why?  The operating system type determines the optimal monitor mode to use, the optimal devices, such as the SCSI controller and the network adapter to use.  It also specifies the correct version of VMware Tools to install.

 

2)   Install VMware Tools on your Virtual Machine.  Why?  VMware Tools installs the Balloon Driver (vmmemctl.sys) which is used for virtual memory reclamation when an ESX host becomes imbalanced on memory usage, alongside optimized drivers and can enable Guest to Host Clock Synchronization to prevent Guest clock drift (Windows Only).

3)   Keep vSwp files in their default location (with VM Disk files).  Why?  vSwp files are used to support overcommitted guest virtual memory on an ESX host.  When a virtual machine is created, the vSwp file is created and its size is set to the amount of Granted Memory given to the virtual machine.  Within a clustered environment, the files should be located within the shared VMFS datastore located on a FC SAN/iSCSI NAS.  This is because of vMotion and the ability to migrate VM Worlds between hosts.  If the vSwp files were stored on a local (ESX) datastore, when the associated guest is vMotioned to another host the corresponding vSwp file has to be copied to that host and can impact performance.

4)   Disable any unused Guest CD or USB devices.  Why?  Because CPU cycles are being used to maintain these connections and you are effectively wasting these resources.

5)   Select a guest operating system that uses fewer “ticks”.  Why?  To keep time, most operating system count periodic timer interrupts or “ticks”.  Counting these ticks can be a real-time issue as ticks may not always be delivered on time or if a tick is lost, time falls behind.  If this happens, ticks are backlogged and then the system delivers ticks faster to catch up.   However, you can mitigate these issues by using guest operating systems which use fewer ticks.  Windows (66Hz to 100Hz) or Linux (250Hz).  It is also recommended to use NTP for Guest to Host Clock Synchronization, KB1006427.

On Monday I’ll go through the Top 5 Don'ts.

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Jamie Baker

Principal Consultant