When we talk about VMware, most of you; probably will think about virtualization, and when we talk about virtualization, the first name that probably comes to mind will be VMware vSphere. VMware's history is strictly related to virtualization, as it was the first commercially successful company to virtualize the x86 architecture (in the late 1990s), making a new era and a new wave in information technology (IT) possible.

IT historical waves were the mainframe, the PC, the network; now they are followed by virtualization and cloud computing shown as follows:

Although the first commercial virtualization product from VMware was Workstation—which was targeted at the client-side server; virtualization, first with GSX, and then with ESX/ESXi, has rapidly grown in importance in just a few years. Server virtualization has become real and accessible to most, but more importantly, it has brought so many advantages (also from an economic point of view) and improved to such a level as to make the virtualization first approach the norm. The VMware vSphere suite includes ESXi (the evolution of ESX Server) for the virtualization layer and vCenter Server for the management layer.

VMware vSphere leverages the power of virtualization to transform data centers into simplified cloud computing infrastructures and enables IT organizations to deliver flexible and reliable IT services. VMware vSphere virtualizes and aggregates the underlying physical hardware resources across multiple systems and provides pools of virtual resources to the data center.

Compute virtualization is only the first step; in order to move to a real cloud computing infrastructure, you will not only need to compute resources abstraction (provided by virtualization), but also operation automation and agility (both of them only partially obtainable through virtualization). Finally, this approach should be applied not only to the compute part but also to the other resources, such as storage, networking, and security.

In 2012, former VMware CTO Steve Herrod explained this vision with the new concept of the software-defined data center (SDDC), where all infrastructure elements (computing, networking, storage, and security) are virtualized and delivered as a service using a cloud computing model:

Virtualization is no longer the final destination of the digital transformation journey; it has become the starting point, an essential requirement, and a foundation for digital businesses. VMware has addressed these needs by extending both its product portfolio and its vision.

VMware has grown its product portfolio with several other products (some of them from important acquisitions, such as Nicira in 2012) in order to accelerate the digital transformation of its customers through a software-defined approach to business and IT. With more than 500,000 customers globally, VMware remains a proven leader not only in virtualization, but also in all technologies related to digital transformation.

But what is digital transformation and why is it so important? All enterprises (but potentially all companies) are becoming digital businesses by using digital technology to drive innovation and new business models. Digital transformation is all about creating new possibilities for the business.

As defined in Gartner, 2016 CEO Survey: The Year of Digital Tenacity, Analyst: Mark Raskino, April 20, 2016:

VMware's vision is to help the digital transformation of those companies by providing flexibility, freedom, and control for the IT infrastructure and services. But the vision has slightly changed through the years. In 2015, VMware's vision was one cloud, any application, and any device, where the one-cloud model was totally based on VMware products and solutions (using the vSphere platform as a common platform).

According to VMware's vision at the time, by having a common platform both on-premises and on the public part, it would have been possible to build a hybrid cloud model, in order to have full portability of your workloads. Unfortunately, the vCloud Air project (an IaaS public cloud service offered by VMware) has not gone as expected (and on May 8, 2017, this asset was sold to OVH), so this vision has changed.

During VMworld 2016, VMware has announced a more realistic vision: any device, any application, any cloud. Not only one cloud, but now any cloud:

VMworld 2017 has confirmed this vision, where vSphere remains the foundation of the underlying infrastructure, at least for the on-premises part, and a new suite has been introduced—VMware Cloud Foundation.

VMware Cloud Foundation is VMware's unified SDDC platform for the hybrid cloud and it's based on VMware's compute, storage, and network virtualization technologies to deliver a native integrated software stack that can be used on-premises for private cloud deployment or run as a service from the public cloud with consistent and simple operations.

The core components of VMware Cloud Foundation are VMware vSphere, Virtual SAN (vSAN) for the storage part, and NSX, for the network and security part. VMware Cloud Foundation also comes with VMware SDDC Manager that automates the entire system life cycle and simplifies software operations as described in the following figure:

In addition, it can be further integrated with VMware vRealize Suite (added in version 2.3), VMware Horizon, and VMware Integrated OpenStack. The idea behind the any-cloud vision is to still have a common part (the VMware Cloud Foundation) to provide resources interoperability and mobility for building an effective hybrid cloud.

Cloud Foundation was released in September 2016 and is actually on version 2.3 (released on December 2017). For the private cloud, you can buy pre-assembled and configured integrated systems directly from different vendors (Dell-EMC with the vxRack SDDC, Fujitsu with PRIMEFLEX, HPE with Synergy, to give some examples) or you can build, assemble, and image with help from a partner or VMware PSO.

For the public cloud, VMware has built some important and strategic partnerships to provide interoperability with VMware Cloud Foundation, initially with IBM (https://www.ibm.com/cloud-computing/solutions/ibm-vmware/) and then also with Amazon AWS (https://www.vmware.com/cloud-services/vmware-cloud-aws.html) with a service sold and supported by VMware as an on-demand, elastically scalable solution. The second one, according to the demos, seems the most promising due to the seamless integration with the vSphere management interface.

VMware Cloud on Amazon Web Services (AWS), actually only available in the US, is a vSphere-based cloud service offered directly by VMware, but with resources and hosting on AWS. The new service will bring our enterprise-class SDDC software to the AWS cloud. And during VMworld EU 2017, other cloud solutions based on VMware vSphere provided by VMware's partners were also announced. The first is VMware HCX (https://cloud.vmware.com/vmware-hcx) that provides application mobility and a cross-cloud infrastructure, initially with IBM and OVH (probably in late 2017). Similar, in the results, to VMware Cloud on AWS, but not sold directly from VMware and more compatible with previous vSphere versions (seems from 5.5). Second, the provider partner program has changed its name and there is a new VMware Cloud Verified status for selected partners.

VMware vSphere remains an important piece of VMware's vision, not only as a cloud OS or an infrastructure part, but also a universal application platform that supports both traditional and next-generation applications (the so-called cloud-native applications). While these two worlds are vastly different, both require infrastructure with the scalability, performance, and availability capabilities needed to meet key business objectives.

VMware vSphere 6.5 also lets you run applications from any cloud, including your data center or in public cloud environments. For this reason, vSphere 6.5 is not only the heart of the SDDC, it's also the foundation of VMware's cloud strategy. vSphere 6.5 is available in both the private cloud and as a service through a public cloud. The new products or solutions, such as VMware Cloud Foundation, VMware Cloud on AWS, and vSphere Integrated Containers, are all built on vSphere 6.5.

To run any application, vSphere 6.5 expands its workload coverage model by focusing on both scale-up and scale-out next-generation applications that are increasingly built using evolving technology building blocks such as containers.

A container image is a lightweight, standalone, executable package of a piece of software that includes everything needed to run it—code, runtime, system tools, system libraries, and settings.

Containers and VMs have similar resource isolation (maybe you can argue that virtualization provides better isolation) and allocation benefits, but function differently because containers do not include the operating system part (or at least not the kernel part of it) and containers are more light, so potentially more portable and efficient.

Docker's website describes in detail the differences between containers and VMs, starting with the architectural difference:

For more details on containers, refer to https://www.docker.com/what-container.

Container technologies have become ubiquitous in the modern data center; their advantages for application packaging are undeniable. Developers are leading the change, adopting container technologies at a rapid rate, and demonstrating their advantages by bringing both new and updated applications to market sooner. One approach in order to solve these challenges could be Containers as a Service (CaaS) to all developers, providing them with better agility but, at the same time, also providing the level of standardization and governance necessary to run containers in production.

So which is best, or why have containers not replaced virtualization yet? There is not a simple answer; for sure, containers are lighter when compared to VMs, but on the other hand, not all applications can run in a container. Put simply, legacy applications will still require VMs, while new applications designed with modern approaches are the ideal candidates to run on containers.

In the vSphere 6.5 release, VMware introduced vSphere Integrated Containers (VIC), a platform to bring containers into an existing vSphere environment in a simple and easy way. With VIC, it is possible to deliver an enterprise container infrastructure that provides not only agility for developers (by using the containers) but also full control for vSphere operations teams, where containers can now be managed with the same concepts and skills as normal VMs, without requiring any changes in processes or tools.

VMware VIC is structured into the following different components:

• VIC Engine: Enterprise container runtime for vSphere that allows developers who are familiar with Docker to develop in containers and deploy them alongside traditional VM-based workloads on vSphere clusters. vSphere admins can manage these workloads through vSphere Web Client in a way that is familiar to them.
• Virtual Container Host (VCH): This is basically a vSphere resource pool used for controlling and consuming some container services, with an isolated Docker API endpoint and a private network. Multiple VCHs can be deployed in an environment, depending on business requirements.
• vSphere Web Client plugin: Administrators interact with VIC through vSphere Web Client, gaining the ability to manage and monitor VIC by means of a plugin. A wizard is available that enables the creation of VCHs.
• Photon OS: This is a small-footprint container runtime for the containers, running on a VM. VIC will run each individual container on a dedicated VM (in order to have the best isolation and security enforcement) with PhonOS on each VM. In order to provide agility during VM provisioning, the new Instant Clone Technology (introduced in vSphere 6) will be used to deliver all VMs very quickly and efficiently.
• VMware Harbor: Enterprise container registry that stores and distributes container images. Harbor extends the Docker distribution open source project by adding the functionalities usually required by an enterprise, such as security, identity, and management.
• VMware Admiral: Management portal that provides a UI for dev teams to provision and manage containers. Cloud administrators can manage container hosts and apply governance to their usage, including capacity quotas, and approval workflows. Advanced capabilities are available when integrated with vRealize Automation.

For more details on the following architecture overview, you can visit the related VMware blog at https://blogs.vmware.com/cloudnative/:

Using VIC, vSphere administrators can provide a full Docker compatible interface to their developers, using the existing vSphere infrastructure with native capabilities and features, including VMware NSX for security and VMware vSAN for storage. The new version 1.2 (released in September 2017) adds a native Docker container host, from a unified management portal.

Customers with current vSphere Enterprise Plus or vSphere Operations Management Enterprise Plus licenses can download the VIC installation packages below.

Other parts, such as Photon OS, are free and available for everybody. It's also interesting to notice that Photon OS Linux is becoming the platform for the VMware virtual appliance, first with the vCenter Server Virtual Appliance, then with NSX controllers (with NSX-v 6.3.3.), and probably with more in the near future.

For more information, see the following:

• vSphere Integrated Containers – Technology Walkthrough: https://blogs.vmware.com/vsphere/2015/10/vsphere-integrated-containers-technology-walkthrough.html
• vSphere Integrated Containers 1.1 Delivers New User Experience Enhancements: https://blogs.vmware.com/cloudnative/2017/04/18/vsphere-integrated-containers-1-1-delivers-new-user-experience-enhancements/
• vSphere Integrated Containers v1.2 Introduces Support for Native Docker Container Hosts: https://blogs.vmware.com/cloudnative/2017/09/12/vsphere-integrated-containers-v1-2/

If virtualization has become mainstream and we are living in a post-virtualization era (that is, the cloud computing wave), does this imply that virtualization is now less important and that hypervisors are just a commodity service? Several experts think so and VMworld 2014 and 2015 may have confirmed this (there were no new vSphere products or features announced, except vSAN and other vSphere related products).

Also, other hypervisors (for example, Hyper-V or Nutanix AHV) have grown really fast both in features and in market share, although VMware vSphere still remains the main solution on-premises (we will not consider public clouds or service providers where KVM, Xen, Hyper-V are the most used platforms).

But the platform is still relevant, at least for VMware, and with vSphere 6.5, they brought attention back to the infrastructure part; vSphere is still needed by several VMware products as a core infrastructure component. Let's see a brief description of some of these products and how they require a vSphere platform.

Since 2014, VMware has also become a storage vendor with an interesting solution called vSAN—a software-based solution to build Hyper-Converged Infrastructure (HCI) systems. With more than 8,000 customers acquired in only a few years and lot of releases, vSAN is the HCI solution that is growing fastest.

But the interesting part is that vSAN is a native vSphere storage solution, that seamlessly extends local storage on each host, making a shared and resilient storage system, and creating a hyper-converged platform that simply works with most of the vSphere skills and all the existing tools, software solutions, and hardware platforms.

VMware has begun to include network and security capabilities in a virtualized computing environment based on vSphere with the vCloud Networking and Security product.

With the Nicira acquisition, this product has been replaced by NSX, a network virtualization solution (or network overlay solution) that enables the creation of entire networks in software and embeds them in the hypervisor layer, abstracted from the underlying physical hardware. All network components can be provisioned in minutes, without the need to modify the application or the physical environment.

NSX-V is tightly integrated with vSphere components requiring both ESXi (used both as a data plane and also for hosting some NFV and VMs used as a control plane) and vCenter (NSX manager is paired with it and the management interface is just an extension of vSphere Web Client). Although, there is also an NSX edition for Linux systems (NSX-T), for NSX-V, the vSphere platform is the foundation.

Cloud computing is the new wave after virtualization and VMware vSphere lacks a true multi-tenant support and partial automation and agility.

For this reason, VMware has several products for cloud management, addressed at private or public cloud scenarios. The most important VMware cloud-capable solutions are vCloud Director (vCD) and vRealize Automation (vRA). VMware vCD was the first product (if we exclude Lab Manager, which was not truly multi-tenant) to bring full cloud capabilities to vSphere.

Actually, this product is still present, but it is reserved only for service providers willing to build and sell public cloud services as part of the VMware vCloud Air Network (vCAN) program based on top of the vSphere platform; these offerings are inherently hybrid-aware and ideal for enterprise-class organizations that want to extend their VMware-based private cloud into the public one.

In 2012, VMware acquired DynamicOps, a provider of cloud automation solutions that enable provisioning and management of IT services across heterogeneous environments. VMware vRA is a product of this acquisition and enables IT automation through the creation and management of personalized infrastructure, application, and custom IT services (XaaS). This IT automation lets you deploy IT services rapidly across a multi-vendor, multi-cloud infrastructure. In this case, the underlying infrastructure could be vSphere-based (probably the most common choice) but vRA can be extended to orchestrate and automate other non-VMware hypervisors and clouds, making possible a true multi-vendor and multi-cloud approach.

Of course, there are other types of cloud management platform (such as OpenStack), but in this case, VMware vSphere could be just a possible choice, not necessarily the main one.

Horizon 7 provides a streamlined approach to delivering, protecting, and managing Virtual Desktop Infrastructure (VDI) and applications while containing costs and ensuring that end users can work anytime, anywhere, across any device.

The Horizon for view part (related to VDI) is tightly integrated with VMware vSphere, requiring both vCenter Server (that is managed by the View Manager and is needed to perform provisioning and VM management) and ESXi (that is used to host the VDIs). There are some exceptions, such as if you are using manual pools of dedicated (and pre-provisioned) VMs.

Also, note that there are now some new offers, such as Horizon Cloud on Microsoft Azure (https://blogs.vmware.com/euc/2017/10/vmware-horizon-cloud-on-microsoft-azure-now-available.html).

Containers do not require virtualization at all, because they can run on bare metal. And you can use different solutions for managing and deploying them.

But in the VMware vision, VMware vSphere is used to provide a CaaS solution with two different approaches:

• Using VIC (previously described), useful if you have containers that you need to put into production and use your existing production VM monitoring systems to monitor individual containers
• Using vRA to deploy VMs (with Photon OS or Core OS) that can host multiple containers

Both approaches have a similar infrastructure and only the management part is different depending on whether you have vRA for cloud management, orchestration, and automation.

And of course, vSphere may be not needed at all, because containers can run on bare metal or other platforms, and be managed by other tools. Also, in this case, VMware can still be present, because Linux-based containers still need an operating system to run on, and VMware Photon OS could be a possible option.

For more information, see Choosing a Container as a Service (CaaS) Solution at https://blogs.vmware.com/services-education-insights/2017/07/choosing-container-service-caas-solution.html.

VMware has a plethora of other products for different segments and some of them could be interesting to adopt in a vSphere environment, for example:

• vRealize Operations: This is a monitoring tool used to improve application performance, prevent business disruptions, and make IT more efficient. There is also a specific SKU of vSphere Essentials Plus that includes the operations component. We will describe some of its features in Chapter 9, Monitoring, Optimizing, and Troubleshooting.
• vRealize Log Insight: This is useful to collect logs from different sources (not necessarily only ESXi hosts) and analyze that data. VMware users with a supported vCenter Server license (version 5.x or 6.x) are entitled to a 25-OSI pack of vRealize Log Insight for vCenter Server (see http://kb.vmware.com/kb/2144909). We will describe some of its features in Chapter 9, Monitoring, Optimizing, and Troubleshooting.
• Site Recovery Manager: This product is an orchestrator to simplify the site disaster recovery plan in a single-click procedure, with the capability to test it in safe mode and to handle not only the fail-over procedures (planned or unplanned) but also fail-backs. This product is designed to manage only disaster recovery (DR) for vSphere environments. We will describe some of its features in Chapter 12, Business Continuity and Disaster Recovery.
• VMware Integrated OpenStack (VIO): This is a VMware supported OpenStack distribution that makes it easier for IT to run a production-grade OpenStack-based deployment on top of their existing VMware vSphere infrastructure.

Even if VMware vSphere seems a minor release, there are many improvements, and changes that could be considered in the same way as a new release with new functionalities and new limits.

VMware vSphere 6.5 became generally available (GA) on November 15, 2016, several years after the initial release of version 6.0 (GA was on March 12, 2012), bringing several new features and improvements to the vSphere platform.

At a high level, the new version focuses on the following four main areas of innovation:

• Simplified customer experience: There are several improvements in vCenter Server Appliance (vCSA) features and capabilities, with a new modern and truly multi-platform client (finally HTML5-based) and a simple REST based API for automation and integration
• Comprehensive built-in security: It uses the well-known policy-driven approach also used for security aspects at scale to secure data, infrastructure, and access
• Universal app platform: Following the VMware vision, vSphere 6.5 could be a single platform to support any application on any cloud as discussed previously
• Proactive data center management: It has become predictive in order to address potential issues before they can become serious issues

At a technical level, the different improvements are as follows:

• Scale enhancements: There are new configuration maximums to support even the largest application environments (see the next paragraph for the different numbers).
• VMware vCSA: This is now the preferred type of vCenter and the core building block for vSphere. Not only does it now have the same features as the Windows version, but it has new specific functions—a native vCenter Server high availability solution, native vCenter Server backup and restore, migration tool from existing vCenter Server (also in a previous version) to vCSA.
• VMware vSphere Update Manager (VUM): In vSphere 6.5, it has been fully integrated with vCSA. This integration eliminates the additional resources required for another VM, OS license, and database dependencies of the previous architecture. Integrated VUM leverages the vPostgres installation that is part of vCSA, but the data is stored using a separate schema.
• VMware Tools: There are several improvements (such as digital signed ISO), but also some changes in supported OS and supported levels, including a bifurcation of VMware Tools for legacy and current guests.
• REST APIs: These are simple, modern developer-friendly APIs to integrate your vSphere environment in other management platforms. Also, other CLIs have been extended and improved.
• vSphere Client: This is a new HTML5-based GUI, similar to the VMware Host Client, that ensures fast performance, cross-platform and multi-OS compatibility. Note that the vCenter installer is now also supported on Microsoft Windows, macOS, and Linux operating systems without the need for any plugins.
• Content library: This was introduced in vCenter 6.0, but with some limitations. Now it's possible to mount an ISO directly from the content library, apply a guest OS customization specification during VM deployment, and update existing templates.
• Security at scale: This is a new policy-driven security framework that makes securing infrastructure operationally simple using the same approach as the already existing policy-driven storage.
• Encryption: VM-level encryption protects unauthorized data access both at rest and in motion.
• Audit-quality logging: There is enhanced logging that provides forensic information about user actions.
• Secure Boot: This protects both the hypervisor and guest operating system by ensuring images have not been tampered with and preventing loading of unauthorized components.
• Proactive HA: There is high availability capability that utilizes server health information and migrates VMs from degraded hosts before a problem occurs.
• Cross-Cloud vMotion: Live migrates workloads between VMware-based clouds.
• Virtual Volumes Replication: Extends Virtual Volumes (vVols) support (introduced in v6.0) with native array vVols replication.
• Virtual NVM Express (NVMe) and others new controllers: With hardware version 13, you can use NVMe, SATA, SCSI, and IDE controllers in a VM.

For more information, see the following links:

• https://www.packtpub.com/virtualization-and-cloud/mastering-vmware-vsphere-65-video
• https://blogs.vmware.com/vsphere/launch
• https://blogs.vmware.com/vsphere/2016/10/introducing-vsphere-6-5.html
• https://featurewalkthrough.vmware.com/#!/vsphere-6-5
• https://www.vmware.com/content/dam/digitalmarketing/vmware/en/pdf/whitepaper/vsphere/vmw-white-paper-vsphr-whats-new-6-5.pdf
• https://blogs.vmware.com/vsphere/2017/07/vsphere-6-5-update-1-hood.html
• http://blogs.vmware.com/vsphere/2016/10/whats-new-in-vsphere-6-5-vcenter-server.html
• http://blogs.vmware.com/vsphere/2016/10/whats-new-in-vsphere-6-5-security.html
• http://blogs.vmware.com/vsphere/2016/10/whats-new-in-vsphere-6-5-host-resource-management-and-operations.html

VMware vSphere 6.5 Update 1 was released on August 2, 2017, and it adds some bug fixes, new features, and also a key additional change in the support and license of vCenter Server:

• vCenter Server Foundation can now manage and support four ESXi hosts: Although three hosts could be enough for smaller environments, VMware has received feedback that three host environments were too small in some small and medium-sized business (SMB) cases. For this reason, vSphere 6.5 Update 1 is now increasing the number of hosts that vCenter Server Foundation will support from three hosts to four.
• vSphere 6.5 general support has been extended: VMware understands that upgrading infrastructure can be a lengthy process. One consideration for whether or not to upgrade is how long the new product will be supported. VMware wants to make the customer's decision to upgrade easier by extending general support for vSphere 6.5 for a full 5 years. This means that support for vSphere 6.5 will now end on November 15, 2021.
• Upgrade path: Direct upgrade from vSphere 6.0 Update 3 is now a supported path (more details on the upgrade path will be provided in Chapter 11, Lifecycle Management, Patching, and Upgrade).
• Adds full support for ESXi on Mac Pro 6,1 hardware: Many customers and home lab users like to use Mac hardware in order to virtualize macOS in an officially supported manner. VMware vSphere 6.5 Update 1 adds full support for ESXi on Mac Pro 6,1 hardware. So, if virtualizing macOS is your thing, you can now do it with the latest hardware and without workarounds.

Also, there are some interesting enhancements, including the following:

• vSphere Client now supports 90% of general workflows and features; the new HTML5-based vSphere Client can now support up to 90% of general workflows. This is welcome news as VMware pushes towards 100% parity between the various clients (considering also that Adobe has recently announced the end of Flash Player support by the end of 2020).
• There is a new version of vSAN 6.6.1 with new capabilities, such as VUM support in order to manage vSAN software upgrades easily.
• VMware vSphere 6.5 Update 1 is required to enable VMware Cloud on AWS.
• New limits for vCenter Server in Linked Mode (see next paragraph, in the numbers specific for vCenter Server).

For more information, consult the release notes at https://docs.vmware.com/en/VMware-vSphere/6.5/rn/vsphere-esxi-651-release-notes.html.

As usual, the maximum numbers are published in a specific document and grouped by types. The vSphere 6.5 configuration maximums guide has already been updated with the new 6.5 U1 numbers (https://docs.vmware.com/en/VMware-vSphere/6.5/vsp-esxi-vcenter-server-651-configuration-maximums-guide.pdf). The most interesting numbers, as compared to the previous versions are described in the following paragraphs.

With this new version of vSphere, there is a new version of the VM virtual hardware (version 13). Some limits and features (virtual RAM, NVMe controllers) are available only with the new virtual hardware 13; other limits are also valid for previous versions of virtual hardware. For more details refer to VMware vSphere Virtual Machine Administration guide at https://docs.vmware.com/en/VMware-vSphere/6.5/com.vmware.vsphere.vm_admin.doc/GUID-789C3913-1053-4850-A0F0-E29C3D32B6DA.htm.

The following table summarizes some of the maximums numbers for each VM in the different version of vSphere:

Those limits can change if you are using VMware FT to protect your VMs and the real limits, in this case, will be lower. More details will be provided in Chapter 13, Advanced Availability in vSphere 6.5.

ESXi hosts limits remain mostly the same from version 6.0 but, of course, new hardware and new devices are now supported. Scalability remains quite similar compared with version 6.0, as summarized in the following table :

* The official document reports 512, but the Disk.MaxLUN advanced settings report 1024 on a ESXi 6.5 host.

In most cases, there is 2x increase from vSphere 5.5.

The vCSA version of vCenter Server will now have the same limits as the Windows installable version (also with the embedded DB). And finally, the vCSA is now the first choice (the Windows version will be deprecated in the next releases), including some new features available only for it. The following table summarizes the different numbers from the different versions of vCenter Servers:

There is a 2x increase as compared to previous vCenter Server 6.0.

Some numbers have been increased with vSphere 6.5 Update 1 when you are using more vCenter in Linked Mode (that defines a vSphere domain):

• Maximum vCenter Servers per vSphere domain: 15 (increased from 10)
• Maximum ESXi hosts per vSphere domain: 5,000 (increased from 4,000)
• Maximum powered on VMs per vSphere domain: 50,000 (increased from 30,000)
• Maximum registered VMs per vSphere domain: 70,000 (increased from 50,000)

Despite the number, vSphere 6.5 does not represent a minor release of vSphere 6.0 but a new major release (the same considerations were possible with vSphere 5.0, 5.1, and 5.5). For this reason, you have to plan carefully whether to upgrade and how to upgrade. Finally, with vSphere 6.5 Update 1, it is possible to upgrade from vSphere 6.0 Update 3 (this was not supported in the previous version of 6.5).

There are several changes but also new features and scalability properties that make vSphere 6.5 interesting for new environments, but also for existing customers.

The main consideration to make with regard to the upgrade is that each new product (it does not matter whether it is a major or a minor release) brings new features, new code, and potentially maybe also new bugs (and the history of vSphere 5.1 and 6.0 has demonstrated that early adopters came across some issues). Of course, upgrading might also fix some existing bugs. But the maturity of a new release might not be the same as the previous versions. So, before upgrading, evaluate the new release by first using it in a dev or test environment or wait a few months to see the first feedback from the community and reported issues, and how and when they have been solved. Some prefer to wait for the first Update 1 version and, finally, it is here. To be honest, the code of the initial 6.5 release already seemed to be more mature than that of version 6.0 in its infancy.

You also have to consider all third-party code, included drivers or services, and kernel modules (for example, PernixData FVP is not compatible with 6.5) or switch extensions (after vSphere 6.5 Update 1, customers using third-party virtual switches such as the IBM DVS 5000v, HPE 5900v, and Cisco Nexus 1000v will need to migrate off of those switches prior to upgrading to any future release), vCenter plugins or integration with external software, for example, backup products. For third-party switches see KB 2149722—Discontinuation of third party vSwitch program at https://kb.vmware.com/kb/2149722.

Remember also that vSphere may be just a foundation of a bigger solution and architecture (as described before); in this case, you have to check every piece of software and hardware to match the compatibility and supported version.

There can be several reasons to upgrade vSphere to the latest version:

• Extend the support and the life cycle of the product: VMware vSphere 5.5 will have an extended support and will reach end of general support in September 2018, VMware vSphere 6.0 on March 2020, and vSphere 6.5 on November 15, 2021.
• Have a new product: It provides new features but also new hardware (and other new software) may require or have some benefit from this version.
• New infrastructure functions: Such as the new high availability features; we will discuss all those functions in upcoming chapters.
• New security functions: Some are really cool and unique, but data at rest protection using encryption could also be possible not only at hypervisor level (in this case only with 6.5) but also at storage level (also vSAN now has this capability).
• Storage benefits: If you are using vVols, you can now have a native replication support (of course, if your storage vendor supports it in vSphere 6.5). If you are using vSAN, the only way to upgrade it and have new features is to upgrade vSphere.
• New web client (vSphere Client): Finally, we have an HTML5 client (not 100% complete, but very close, at least for operational tasks) for the vCenter Server graphical management. For the ESXi host, there was already (starting from 6.0 Update 2). Note that you can add both the HTML5 clients to the previous version using Flings software (https://labs.vmware.com/flings).
• New vCSA: The new virtual appliance for vCenter is definitely the first choice, due to the full capabilities and also for the new functions.

There can be few reasons to skip the upgrade to vSphere 6.5 which are as follows:

• Is it compatible? You may have a software or hardware part that does not support this version. Note that from the next version of vSphere, several generations of servers will probably no longer be supported (for example, if you install ESXi 6.5 on a Dell 11g, it reports that the next version of ESXi will no longer support that processor).
• Does it support existing servers? vSphere 6.5 drops the support to some old hardware and software. vSphere 6.5 no longer supports the following processors—Intel Xeon 51xx series, Xeon 30xx series, Xeon 32xx series, Xeon 53xx series, Xeon 72xx/73xx series.
• Do you really need the new functions? If you are involved in a digital transformation, you will probably need the new platform (AWS for vSphere or vSphere for integrated containers management require the new version). But for SMBs, most of the new functions are not usable or useful yet.
• Can you really use the new functions? Most of the new features are only for the Enterprise Plus edition (see the next paragraph for more details about the different editions).
• Is it mature and stable enough? As mentioned previously, vSphere 6.5 seems a better code compared to previous version 6.0 (or also 5.1) when it was released in GA. Also, it has already been used in production environments for more than 6 months, with few bugs.

VMware vSphere is licensed in different ways and different packages and bundles, usually identified by a stock keeping unit (SKU) code. There are some bundles (like vSphere with Operations Management Enterprise Plus), OEM, ROBO and VDI specific SKU, or other license models (such as ELA) that we will not consider and describe.

For more details, you can consult the official VMware (vSphere) licensing page at https://www.vmware.com/support/support-resources/licensing.html.

For VMware vCenter Server, the licensing model is quite simple per instance and with three different editions:

For ESXi, the license is entitled per socket (except in some specific bundle or SKU, such as ROBO or VDI) and there are different editions with different features.

Note that since June 30, 2016, the ESXi Enterprise, vSphere with Operations Management Standard/Enterprise editions are no longer available. Customers who already own Enterprise versions are not yet affected (their current editions will continue to be supported through the EOA of vSphere 6):

For ESXi, there are also the Free Hypervisor and the Essential editions; both are quite limited in function (no cluster function at all) but do not have specific limitations on the resources at the level of a single host.

The Free Hypervisor edition does not include the VDAP API, that means no native backup capability for all the backup software that uses that interface, and does not include either the vCenter Agent, that means no way to manage from vCenter.

For SMB, there are two specific bundles—vSphere Essential and Essential Plus Kit, that combine one instance of vCenter Essential and six licenses (usable on a maximum of three hosts) of ESXi Essential or Essential Plus. Both bundles have an interesting price, making virtualization also possible for companies with budget constraints.

For enterprises, depending on the size and the business requirements, for ESXi licensing, usually Standard or the Enterprise Plus can be used.

This chapter has covered a general overview of all the products, solutions, and features of the vSphere 6.5 suite, comparing the evolution with the previous releases.

In this chapter, we have explained why you should choose (or not choose) vSphere 6.5 compared to the previous version or other products. Also, it briefly describes the different editions and licenses of vSphere.

Finally, it also includes a general overview of all the products, solutions, and features in other VMware products or different suites that could be complementary or where vSphere represents an infrastructure foundation.

Next chapter, will be focused on how to plan a virtualization project in order to build a good infrastructure.