Upgrading to VMware vSphere: Five pros and five cons

Increased performance, scalability and new features top the list as to why you should upgrade to vSphere, but proven product stability, third-party product and hardware compatibility are reasons you may want to stay with VMware Infrastructure 3 for now.

There are some compelling reasons to upgrade to vSphere but also reasons why you may not want to. For some it makes sense to upgrade and many have already done so, for others VMware Infrastructure 3 may work just fine. Others may be waiting for a time where it makes more sense to upgrade, such as an upcoming server hardware refresh.

Depending on your environment and requirements, the reasons I offer in this article may help you to decide whether or not to upgrade to vSphere.

Why upgrade to vSphere?

1. Performance and scalability
VMware vSphere has proven to be much faster in almost every area compared to VI3, from CPU to storage to networking. The result is better efficiency and performance which will benefit applications and allow for better virtual machine (VM) density on host servers. Scalability has also been increased for both hosts and VMs as follows:


  VI3 vSphere
Maximum VM vCPUs 4 8
Maximum VM Memory 64 GB 255 GB
Maximum Host CPU Cores 32 64
Maximum Host Memory 256 GB 1 TB

Because of these improvements, applications will perform better on vSphere and you can now virtualize almost any workload. For a complete overview of the performance related enhancements in vSphere see this white paper from VMware.

2. Features and add-ons
VMware vSphere has no shortage of new features including a few major ones and very many smaller ones. Some of these features could be very beneficial to your environment and fulfill shortcomings you may have in certain areas. Some of the major new features include the following:

  • Fault Tolerance – While it has some limitations, this new feature takes high availability to the next level by providing continuous availability for critical VMs by providing protection against a host failure. In some cases this feature could replace the use of Microsoft Cluster Server to provide protection against a VM going down due to a host failure, however it does not protect against an application failure.


  • vShield Zones – This feature that is included in several vSphere editions provides network security for VMs using virtual firewall appliances; previously third-party products were needed for this.


  • VMware Data Recovery – This feature that is included in several vSphere editions provides a disk-to-disk backup application for protecting virtual machine data; previously third-party products were needed for this.


  • Distributed/third-party vSwitches – This feature allows for easier vSwitch administration and configuration as well as enhanced integration using the Cisco Nexus 1000v.

Along with these features improvements to Thin Provisioning, Storage VMotion, Distributed Power Management and some additional new features such as Host Profiles, VMDirectPath, paravirtualized SCSI adapters and vCenter Server Linked Mode provide some compelling reasons to upgrade to vSphere.

3. Support
The clock is ticking for VI3 support. VMware lists the end of general support for VI3.5 on 5/21/2010, which means VMware will no longer certify new hardware for VI3.5. Extended support, however, will be available to May 21 2013, so patches and technical support will still be available.

As vSphere is VMware's focus, VMware will likely be improving the current release and developing new releases for vSphere. The same holds true for technical support, as time goes by and more customers will be using vSphere, the technicians who provide support will be most familiar with vSphere and problems with VI3 may take longer to resolve. Therefore upgrading to vSphere would be beneficial to ensure you get the best support possible.

4. Cost savings
We all know virtualization can help save you money but vSphere can help save you even more money than VI3. First, Distributed Power Management is now fully supported in vSphere which can move workloads around and power down hosts when they are not needed. Second, because vSphere offers better scalability than VI3 you are able to have higher virtual machine density on your hosts, which means you may need less physical hardware then you did with VI3.

5. Update 1
New major dot zero releases are sometimes buggy and VMware's recent track record when it comes to bugs may have many nervous about upgrading to it right away. Now that Update 1 has been released, most of the major bugs should have been found and fixed. So far vSphere has proven to fairly stable and now that Update 1 is released you should consider upgrading.

Why stay with VI3?
While there are several reasons you may want to upgrade to vSphere, there are other reasons you may want to stick with VI3 for now.

1. VI3 is very stable
VI3 is solid as a rock; it's been out for three years, has been very stable and at this point is a very mature product that works very well. If VI3 works well for you and you don't need any of the new features that vSphere has, then why upgrade? Some people are still using very old operating systems like Windows NT because it suits their needs.

An upgrade of an existing environment can sometimes be a troublesome, distributive process and if the benefits are just not there for you then why upgrade. General support will end for VI3 next year but that shouldn't deter you from continuing to use it. Extended support will continue until 2013 which will ensure you receive new patches and technical guidance will continue to 2015 which provides online support for low severity issues.

2. Supported hardware
VMware vSphere requires 64-bit server hardware and will not run on older 32-bit hardware. Additionally, some of the new features in vSphere like Fault Tolerance require specific newer server hardware. Therefore if you have older hardware that is incapable of running vSphere you will have to hold off until you can afford to buy new server hardware that can support vSphere. In addition, you may have older server and storage hardware that works just fine with VI3 may not be supported by vSphere.

3. Third-party product compatibility
When vSphere was first released there were many third party applications that did not support it, this includes some of VMware's own products such as Lab Manager and View. Vendors have slowly releasednew versions of their products that support vSphere, but there are some that still do not. If you do not have an active maintenance contract with a vendor you may not to pay to upgrade to a newer version that supports vSphere. Additionally you may have your own custom scripts and applications that work with VI3 but not with vSphere. You will need to take time to ensure compatibility and that they work properly with vSphere.

4. Skills
While vSphere is not radically different from VI3 it is still different enough that you should make sure you are familiar with it before upgrading to it. There are some things that have changed in vSphere and you need to be aware of them to avoid potential problems. Spending time getting familiar with the new release and taking a training course is recommended before you upgrade.

5. Licensing costs
If you do not have active service and support contract (SnS) on VI3 with VMware you are not entitled to vSphere. Therefore you will have to spend money either renewing your SnS or purchasing vSphere licenses to be able to use it.

In addition, customers with Enterprise edition licenses will find they no longer have the top tier license with vSphere. VMware added an Enterprise Plus edition that existing Enterprise Plus customers are not entitled to unless they pay extra licensing fees. The Enterprise Plus license is necessary if you wish to use advanced features such as Host Profiles and distributedor third-party vSwitches as well as have maximum scalability (eight-way vSMP, 12 cores/processor, >256GB host memory).

Whether you choose to upgrade or not, both VI3 and vSphere are sturdy products.


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.

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