The virtualization world was very excited for the release of VMware ESX 3.5 and Virtual Center 2.5 last week. However, should everyone jump on to the new platforms quickly? I say no. To be fair to myself, I have performed a limited set of upgrades already within the week, and some are planned over the next few weeks. Yes there was a beta process. Yes VMware generally publishes good software. Yes I know these are not Microsoft products. But here is why I say no to ‘jumping’ onto an upgrade immediately for virtualization products:
The inherent nature of virtualization reaches scope farther than one system as it has historically. With a single ESX server hosting upwards of 30 virtual machines, the magnitude is amplified should there be an issue. So, as with anything critical – a test environment is a must. The development environment may be a small number of ESX servers that hold non-critical virtual machines so you can accept any risks that may arise in your upgrade.
Cover Your Bases
Be sure you are able to execute all scenarios with great confidence before proceeding into the upgrades. One example I will deal with soon is I will have a large number of critical virtual machines hosted on ESX 3.02. If I take one server into maintenance mode, then upgrade it to ESX 3.5 can I migrate from the 3.02 to the 3.5 systems without issue while online? I did upgrade Virtual Center to 2.5, so that was a good starting point for my 3.02 to 3.5 upgrades. VMware has put out release notes with a list of Known Issues with ESX 3.5 and Virtual Center 2.5 that are a good starting point to identify your migration upward in the ESX and Virtual Center versioning.
Upgrade or New Install? You Decide
ESX is released as a full/new install (as a CD ISO) or an upgrade (tar file) installation. I personally will go for the new install mechanism rather than the upgrade. This is because I find the ESX install quite straightforward and easy and rebuilding an ESX host can be done in very little time at all. With the rebuild process very quick for ESX and most management and configuration elements configured from Virtual Center, ESX is unique in build time requirements.
Old School Wait and See
Many people offer the old adage “Wait six months before upgrading” or some other variable time frame when core updates or service packs are available. This is to let other people “work out the bugs” in software before you have to deal with them. There is little basis in virtualization for this logic, but many people have adopted it as a policy related to updates. VMware is unique as new core functionality like Storage VMotion is available with ESX 3.5 and I know I am very excited for this new functionality. This ultimately is your call, but the best advice before anything is to get informed on the product releases and the known issues instead of starting a blind installation.