VMware ESX 3.5 and VirtualCenter 2.5 small features guide

VMware ESX 3.5 and VirtualCenter 2.5 deliver new features and functionality, but some of the smaller additions have been buried under big changes. Here is a quick guide to some of the lesser-known ESX 3.5 features.

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ESX 3.5 and VirtualCenter 2.5, VMware's latest offerings, deliver some major new features and functionality (ie. Storage vMotion, Update Manager) but also include many smaller changes that many users will find extremely useful. I've summarized some of these new features in this article. Many of these features address issues raised in the previous release and will make administration much easier for VMware admins.

VM BIOS Delay
One new feature, VM BIOS Delay setting, is very handy if you are trying to get to the Boot menu to boot from a CD-ROM. Prior to 3.5, the VMware BIOS screen only showed for a very brief second or two, which made it difficult to get to the BIOS Setup Menu (F2) or Boot Device Menu (ESC). You can now edit the VM's settings.

There is a boot options selection under advanced on the options tab, too. Here you can set a power-on boot delay in milli-seconds as well force the VM to enter the BIOS the next time the virtual machine boots.

VM swap file Location
You can now specify a global location for your VM's vswp files on an ESX host. Vswp files are created when a VM is powered on and deleted when a VM is powered off. This file is used only when an overcommitted host has exhausted all of its physical memory.

By default, this file is equal to the amount of RAM assigned to a VM. If you use memory reservations on a VM this will reduce the size of this vswp file: vswp file size = vm ram amount – memory reservation amount. To change this setting, go into Configuration -> Virtual Machine Swap File Location on the VI Client. You can change the setting to store the vswp files on another datastore.

Be warned though. If the datastore you select is not seen by all ESX hosts (such as local storage) then vMotion and DRS will not work. You can still specify an alternate location for your VM's vswp file on an individual basis by editing the VM's vmx file.

ESX NTP time configuration
You no longer have to edit text files on the Service Console to configure ESX to sync to an NTP time server. They can be set using the following steps:

  • go to VI Client under Configuration -> Time Configuration,
  • click the Properties link,
  • check the 'NTP Client Enabled' box under the NTP Configuration section,
  • click the Options button and select Start and Stop with Host in the General section,
  • Click the NTP settings section,
  • click the Add button to add a NTP server (or multiple servers). You can remove 127.127.1.0 which is the local system clock here,
  • click OK to apply your changes and start service.
The ESX built-in firewall will automatically be modified to allow outgoing connections on port 123. Your server clock should shortly start syncing with the NTP server you selected. You can check the current time by clicking the Refresh link in the VI Client.

VM Summary
VMware made a few changes to the VM Summary tab. Prior to VC 2.5, if a VM had more then one IP address only one would be shown. Additionally, there was no way to control which IP address displayed. Now, all IP addresses for the VM are displayed.

A new field called Memory Overhead has been added. This is the extra space needed by the ESX Server host for its own code and data structures beyond the memory allocated to each virtual machine. Overhead will vary based on the amount of CPU and RAM assigned to a VM. More detail on this can be found in the Resource Management Guide, Chapter 9 – Advanced Resource Management.

Another new section, Annotations, has been added. This section replaces Notes in prior versions. Notes can still be added, as well as custom attributes that can be displayed on both the VM summary page and the Host/Data Center/Cluster VM page. Custom attribute functionality was available in prior versions but could not be displayed on the VM summary page.

Grow virtual disks
It is not uncommon for users to create a VM, install their OS and configure the server only to find out later it had not been given enough disk space. Additional virtual disks can always be added to the VM, but in some cases increasing the size of existing partitions is really what's needed.

Prior to 3.5 you had to use the Service Console vmkfstools command to increase the size of a vmdk file. But now the VI Client can be used to grow virtual disks. Keep in mind that growing a virtual disk only increases the size of the vmdk disk file. It will not automatically increase the size of your OS disk partitions. This must be done manually afterwards. A variety of methods can be used, including OS tools, boot CD's (e.g. Knoppix) and other utilities.

Follow these steps to increase the size of an existing virtual disk:

  • First, power off the VM,
  • Choose Edit the Settings for the VM,
  • select the virtual disk you want to increase. A new field will be added under Capacity called New Size,
  • enter a new value that is larger then the current value and your disk file will instantly be increased to the new size,
  • power on the VM and the operating will recognize this new disk space.

Network MAC Address
Setting a fixed MAC address for your virtual NIC(s) as a result of software licensing and other reasons is often necessary. A VM's MAC address will change if the location of the VM changes, i.e. different path on the same host. The VM's location doesn't change during a VMotion hot migration. This is also true of a VM that changes hosts due to HA/DRS migration. But the VM's location does change during a cold migration. So, the MAC address of the VM will change.

Changing MAC addresses has previously been possible, but required users to manually edit the VMX file for the VM changing locations. Optionally, this is possible via the operating system. But now MAC address changes can be done in the VI Client by editing the settings of the VM.

To start, the VM must be powered off. Select the network adapter that you want to change the MAC address and change the setting from automatic to manual. The first three octets of the address will default to VMware's assigned range of 00:50:56. You can enter the last 3 octets as valid hex numbers in the range of 00 – 3f (4th octet) and 00 – ff (5th & 6th octets). Be careful that you do not use a MAC address of an existing VM or there will be conflicts on your network.

These are just a few of the new changes in this latest release from VMware. There are many other new features and changes that VMware has made that users will also find extremely useful. Storage VMotion and Update Manager are two new features that are a bit raw in their current state. They will need to evolve for better integration into the product and greater ease of use. VMware is continually enhancing their products to stay on top in an increasingly competitive virtualization market and we will hopefully see many more improvements in the next release.

ABOUT THE AUTHOR: Eric Siebert is a 25-year IT veteran with experience in programming, networking, telecom and systems administration. He is a guru-status moderator on the VMware community VMTN forums and maintains VMware-land.com, a VI3 information site.

This was first published in February 2008

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