Since I am an independent consultant and VMware Communities Guru, I have recently been asked many questions about whether or not to upgrade to VMware vSphere 4. My answers depends on the following items:
- The hardware involved. VMware vSphere has certain hardware requriements, if your target hosts do not support these minimal requirements, then they are not good candidates for running VMware vSphere. The basic requirements are:
- 64 Bit CPU support. This does mean that some EMT64 machines will work. However they may not be on the VMware Hardware Compatibility Guides.
- Intel-VT or AMD-V support. This pretty much goes without saying; it is impossible to use VMware vSphere if these features are not enabled within the BIOS.
- No eXecute (NX) or eXecute Disable (XD) support within the BIOS. In some cases you are required to enable this bit to allow VMware vSphere to run.
Whether or not the hardware is fully supported by VMware for VMware vSphere 4. This implies that the hardware and IO devices you are planning to use are listed within the VMware Hardware Compatibility Guides. If they are not then there is a chance that when you call for VMware Support that they will deny you this support. It does not happen often but it is possible, so be aware of this. If you are not using VMware vSphere 4 in production, this may not be a huge issue as many a whitebox will work, just be sure your IO devices are listed within the VMware Hardware Compatibility Guides.
- Whether or not current management agents exist for VMware vSphere 4. This implies that your current crop of management agents, such as HP Insight Management Agents, are available for VMware vSphere 4. Monitoring of your physical hardware and alerting on issues is too important to not have available if your use VMware vSphere 4.
- Have you tested vSphere 4 in your environment? Wanting to upgrade implies that you have tested vSphere 4 within your environment and that you are comfortable with the changes in licensing and operation of this .0 release of software. It is unwise to just place VMware vSphere 4 into production without first running some tests. How much of a test plan you use depends on your existing testing processes, but some testing is required. If you are upgrading, at minimum you should test to see which path is a smoother transition for you: upgrading or reinstalling.
- Have you considered licensing level changes? There are many licensing level changes within VMware vSphere 4 with respect to what is available at each license level. If you upgrade will you also need to upgrade your licenses to maintain the appropriate levels of functionality. DRS is a case in point. It is important to know exactly what your licenses imply when you upgrade. With new starts of VMware ESX, it is also important to understand your license levels.
- Do you need to upgrade your hardware to use all vSphere 4.0 functions? In some cases, before you can utilize all features of VMware vSphere 4 such as Fault Tolerance you will need to also upgrade your processors. Not every processor supports VMware vLockstep. If you do require VMware Fault Tolerance, for example, it is important to know its limitations and the required CPUs.
These are not all of the issues involved with upgrading to VMware vSphere 4, but they are helpful considerations for deciding if you should upgrade or even can upgrade as well as start using VMware vSphere 4 for new installations.
As with any virtualization endeavor, it is extremely import to architect, design, and plan your vSphere 4 installations or upgrades. It is very easy to install VMware vSphere 4 without doing any planning, but if you do so, expect frustration, delays, and long days and nights. Ask the tough questions during your planning stages and do not rush to implement vSphere 4 unless there is a major need to do so.