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The new VMware vSphere 5.5 has some interesting new features and scalability properties that make interesting for each new environment, but also for existing customers (considering that the license key remain still the same of the 5.x feature). So could make sense start using directly this version instead of the 5.1 and upgrade all existing environment to the new version 5.5?

Like each new version you have to make some consideration first and especially before starting the upgrade procedure.

The main consideration is that each new product (does not matter that is a major or a minor release) bring new features and so maybe new bugs. Of course it may fix some existing bugs. But it’s maturity may be not the same of the previous versions. So make sense first start using it on a dev/test environment or wait some months to see first feedbacks and also first issues. To be honest this new version has very few new issues compared on what was happened with version 5.1, but of course you have to read the Release Notes and check the VMware KB web site.

Another good point is that most of the VMware new functions related to a new version are usually put in the maximum edition (Enterprise+ for the ESXi) and some already existing may be shifted to lower editions (like has happen with vSphere 5.1 and features like CPU/Mem Hot Add or Storage vMotion moved from the Enterprise to the Standard edition). But for the 5.5 version nothing (except the maximum number of vCPU) has been moved from the highest edition to the lowest. So most of the news are also for big Enterprise or who have the Enterprise+ editions.

Another point is that each version has it’s own HCL, both for hardware AND also for software components. It’s not the same and a compatibility for 5.1 does not imply also a compatibility for 5.5 (or vice versa). So check it before and plan careful your migration or upgrade.

This apply also for backup solutions: if you are using traditional approach with an agent inside each VM probably nothing is affects, but if you probably are using a native backup solution (or something that use the VMware VADP API). Of course new version of VMware VDP and VDP Advanced fully support the new 5.5. But finally also some backup products are releasing new versions or new patches of their backup products (like Veeam Backup & Replicator and Symantec Backup Exec).

Remember also that the transition to the new vSphere Web Client (started with version 5.1) is not yet completed. For some tasks you still need the old vSphere Client (but now with a lot of new limitations compared the Web one).

Here a list of some reason to upgrade and to do not upgrade to the new vSphere 5.5:

Reason Why upgrade Why not upgrade
Because is a new product Mean a new HCL and new features. Possible benefit of new features Mean a new HCL, not necessary the existing hardware or the software are compatible
Because there are a lot of new functions Some are really cool, although maybe there are some third part software that may implement similar features Most of the new features are only for the Enterprise+ edition
Because I already have the license Good point… If you have a vSphere 5.x you can upgrade to 5.5 for free Consider before do some changes in a production enviroment and check the HCL!
Flash Read Cache can improve the storage Yes, but depending of your workloads It’s only for Enterprise+ and/or there are also other host cache solutions
Virtualize Business Critical Applications (BCA) Host scalability, reliable memory, low latency application and AppHA could be interesting for BCA Most BCA could be virtualized also on vSphere 5.x
I want use VSAN VSAN is really cool and could be a new mode to approach the storage VSAN actually is only in beta and it’s not clear how much will cost and which edition can use it
I want use NSX NSX can really change networking NSX will be an Enterprise level solution
I want use virtual hardware 10 Some new features for VDI or Unix VMs In most cases is not necessary and could not be edited from the vSphere Client
I need vmdk greater than 2 TB New limit is 62 TB But note that there are several limitation on “big” vmdk
New vCenter virtual appliance is really scalable With the internal DB can scale up to 100 hosts or 3000 VMs But there are still some limitation with the VA version
Web Client will be the future New version is really faster compared to 5.1 More resources must be planned and note that still you need the old vSphere Client for some tasks
vSphere Client is boring The nversion is less important and required But you still need it, and had several limitation, included that does not support Windows XP and cannot edit VM with virtual hardware 10
SSO is too complex Lot of improvements in this version and the DB is no more required! Some possible issue during the upgrade; be sure to check release notes and KB

With this post I don’t want to discourage the migration to 5.5 (that it’s almost simple if you are starting from 5.1) or say that you have to wait first for an update 1 version. Just know and understand pros and cons before any changing in your environment!

For more information about the know issue of this new release see also: Top 20 vSphere 5.5 Support Topics.


Virtualization, Cloud and Storage Architect. Tech Field delegate. VMUG IT Co-Founder and board member. VMware VMTN Moderator and vExpert 2010-24. Dell TechCenter Rockstar 2014-15. Microsoft MVP 2014-16. Veeam Vanguard 2015-23. Nutanix NTC 2014-20. Several certifications including: VCDX-DCV, VCP-DCV/DT/Cloud, VCAP-DCA/DCD/CIA/CID/DTA/DTD, MCSA, MCSE, MCITP, CCA, NPP.