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Now that the new VMware vSphere 6.5 is in GA, most people are starting considering to upgrade (or start from scratch) with this version, instead of vSphere 6.0 (or also 5.5).

But please consider this product like a major release, there are several changes, but also new features and scalability properties that make interesting for each new environment, but also for existing customers (with an active subscription if you have a 5.5 version, 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.

The 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 seems much better than version 6.0 (that got some critical bugs in the first year of life, but still less 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 6.0 does not imply also a compatibility for 6.5 (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 (that now include also VDP Advanced) fully support the new 6.5. Compared to version 6.0 seems that backup programs are upgrading faster.

And more attention on HCI environment or specific ESXi kernel mode components, like host caching product!

Remember also that the legacy Windows vSphere Client is no more available.  but is running a transition to the old vSphere Web Client (started with version 5.1) based on Flash to a new Web Client totally in HTML5 (but still with limited functions, for the vCenter part).

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 6.0 – Upgrade or not upgrade?):

HCI environmentAn hypercoverged solution imply that the entire stack should be compliant and compatible!Unless you have VSAN, you probably cannot upgrade so soon (for example Nutanix does not support vSphere 6.5)

Reason Why upgrade Why not upgrade
Because it has a longer lifecycle VMware vSphere 5.5 will have an extended support and will go to End of General Support in September 2018!
VMware vSphere 6.0 and 6.5 on March 2020!
VMware vSphere 6.0 has the same deadline
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 and 6.0 have a good support… Also remember that vSphere 6.x supports only processors available after June (third quarter) 2006!
Because I’m acquiring new license All new licenses are vSphere 6.x As written it’s something new… remember that you can downgrade a vSphere 6.x license to a 5.x license
Because of Virtual Volumes It was a big new in version 6.0 and if your storage support them, could be the first step to have new features at storage side In version 6.5 there are some improvements, but remember that not all VVols implementation are the same
Becase of VSAN The only way to have VSAN 6.5 is upgrade ESXi to version 6.5 Remember to check the upgrade guide and follow it well
Web Client will be the future New version is really faster compared to previous version Now there are two different Web Client for managing vCenter
Host Web Client is simple This HTML5 is very effective for managing a host Whas available also in version 6.0U2
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 12 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
vCenter HA configurations Finally there are not only solutions for the Windows version, but also the appliance HA Configuration for the appliance is not so simple (but neither so complex)
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
New vCenter virtual appliance is the first choice Finally the vCSA is full features and could be considered the first choice. A migration tool (to the vCSA) it’s also available! It’s possible just start to upgrade only the vCenter part, and still use old ESXi (if you need them)
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 6.5 is not available yet.
Virtual Machine encryption This is probably the biggest new feature Be careful with the infracture and how can impact other components, like replication or backup
Host caching VMware still provide read only cache and only on Enterprise Plus. VAIO has been improved, but still few products support it. If you are using PernixData (or similar products not available for version 6.5) you need a replacement or remain on version 6.0 or old.

With this post I don’t want to discourage the migration or the upgrade to 6.5 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 few VMware products may benot yet compatible with vSphere 6.5, or at least require a recent version: for example NSX (for vSphere) require at least version 6.3.0, for Horizon version 7.0.2 is the minum requirement. But vCloud Director (actually in version 8.1) still does not support version 6.5

See also: VMware vSphere 6.0 – Upgrade or not upgrade?