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The new VMware vSphere 6.0 has so much interesting new features and scalability properties that make interesting for each new environment, but also for existing customers (with an active subscription, so that you can also upgrade your 5.x license keys).

But like each new version you have to make some consideration first and especially before starting the upgrade procedure, so be sure to start from the vSphere Upgrade Center, the VMware Product Interoperability Matrix, the VMware Compatibility Guide, but also read the following notes.

UpgradeThe main consideration is that each new product (does not matter that is a major or a minor release) bring new features, new code and so potentially maybe also 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 got a very long beta period and validation so I will expect 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 point is that each version has it’s own compatibility list, both for hardware (HCL) AND also for software components. It’s not the same and a compatibility for 5.5 does not imply also a compatibility for 6.0 (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 (that now include also VDP Advanced) fully support the new 6.0. Actually one the first backup vendor to have vSphere 6 compatibility is Symantec, but also Veeam is working on it and others will follow in the next weeks/months.

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

Here is a list of some reason to upgrade and to do not upgrade to the new vSphere 6.0 (the list is similar to the one related on VMware vSphere 5.5 – Upgrade or not upgrade?):

Reason Why upgrade Why not upgrade
Because it has a longer lifecycle VMware vSphere 5.0 and 5.1 will go to End of General Support in August 2016!
VMware vSphere 6.0 on March 2020!
VMware vSphere 5.5 will have an extended support and will go to End of General Support in September 2018!
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. Be sure also to have the new license keys before start the upgrade!
And still remember that is a new product… not so tested as the 5.5 version!
Because there are a lot of new functions Some are really cool Most of the new features are only for the Enterprise+ edition (but this time there is something also from the Standard edition)
Because I have new hardware It support new architectures (the latest x86 chip sets, devices, drivers and guest operating systems) Also version 5.5 has a good support… Also remember that vSphere 6.0 supports only processors available after June (third quarter) 2006!
Because I’m acquiring new license All new licenses are vSphere 6.0 As written it’s something new… remember that you can downgrade a vSphere 6.0 license to a 5.x license
Because of Virtual Volumes This is a big new and if your storage support them, could be the first step to have new features at storage side It’s new… require new storage firmware… It’s not clear if (or at least when) backup programs will support them (especially with the SAN transpor mode)
Becase of the new VSAN If you are already using VSAN this could be a good reason Remember to check the upgrade guide and follow it well
Becase of the new vMotion The new vMotion can work across tradition boundaries Be sure the verify all the requirements, included bandwith and latency (for the long distance vMotion)
Becase of the new FT With support of backup snapshot and multi-processor can be used also for business critical applications New FT is totally different from previous one… remember that also the storage resources are now doubled
Virtualize Business Critical Applications (BCA) Host and VM scalability, and the new FT, could be interesting for BCA Most BCA could be virtualized also on vSphere 5.x
I want use virtual hardware 11 Some new scalability features (note that vSphere 6.0 support VM from virtual hardware 4!) In most cases is not necessary and virtual hardware 8 or 9 can still work fine
I need vmdk greater than 2 TB New limit is 62 TB The size limit remain the same of the version 5.5 but with more limitation on “jumbo” vmdk
New vCenter virtual appliance is really scalable Also now it’s fully comparable with all features and has several deployment options It’s just something new, but seems very good
Web Client will be the future New version is really faster compared to 5.1, but also with 5.5 More resources must be planned and note that still you need the old vSphere Client for some tasks
I’m using 3rd part backup solution If agent based (like in physical systems) you can upgrade, otherwise you have to wait for the new compatibility Be sure to wait for new compatibility and verify it (for example with Virtual Volumes, or FT)!
I’m using VDP Now it include also the Advantage edition and it’s fully compatible with vSphere 6.0 Of course, there are other also backup products
I planning a P2V Be sure to have the right tools The Standalone Converter 6.0 is not available yet.
“I hate SSO” The new vCenter architecture is better Was already good enough also in 5.5 (at least only the SSO part)

With this post I don’t want to discourage the migration to 6.0 (that it’s almost simple if you are starting from a 5.x) 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!

Remember also that some few VMware products are not yet compatible with vSphere 6.0: for example NSX for vSphere 6.1.2 is not compatible (version 6.1.3 add compatibility, but still with some limits described in this KB). For Horizon the new 6.1 version fully support both vSphere and VSAN 6.0.

Please note that there is an issue in CBT in ESXi 6.0 that can impact your upgrade decision, also if your backup program will already support vSphere 6.0: for more information see KB 2114076 (Backing up a virtual machine with Change Block Tracking (CBT) enabled fails after upgrading to or installing VMware ESXi 6.0). On mid May VMware has released the patch for this major CBT issue.

On Nov 2015, another critical issue that affect all vSphere 6 releases has been discover, still on Change Block Tracking (CBT) and actually without a patch. For more information see KB2136854 (Backups with Changed Block Tracking can return incorrect changed sectors in ESXi 6.0).

See also: When Should I Upgrade to VMware vSphere 6?


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.