vSphere Host Design Considerations

Host is the most important and critical object of vSphere Design as it would be hosting all the Virtual Machines and would provide the direct access to 4 major components i.e., Memory, CPU, Network and Storage (connection to SAN through I/O ports). Any Design consideration is derived only to fulfill the Application Requirements and its availability.

Before concluding on type of Physical Hosts, the architect has to go through lot of Design Considerations. I have tried to represent this through a mind map, inspired by Scott Lowe’s training video (Designing Vmware Infrastructure) and Vmware vSphere Design book. Below are some of the Design considerations

Ø   First understand the nature of Application, i.e., whether it is CPU or Memory Intensive or requires high Storage or Network I/O.

Ø  Estimate the peak Resource utilization or Resource recommendations for new workloads from respective application/OS vendors.

Ø  If the Applications are CPU or RAM intensive then proper ratio of CPU and RAM needs to manipulated for physical server.

Ø  If the applications needs high Storage IOPS then find out which type of connectivity would be required to meet the application requirements, i.e., FC, iSCSI or NFS. This gives an idea how many HBA’s would be required. Similarly with Networking whether you need fewer 10 GB cards or many 1 GB cards.

Scale UP or Scale OUT:

It is Fewer Large Servers vs More Smaller Servers, this is the main consideration in finalizing the physical server hardware, once we have the above information through initial meetings and evaluations we can finalize on type of server. Both Rack and Blade server comes in higher densities (Higher CPU & RAM), Scale UP provides higher consolidation ratio or lets you run very large VMs. One major consequence would be during physical host failure, where the cluster has to restart many VMs on rest of fewer servers for HA. The benefits of both Scale UP and Scale OUT is mentioned in the above mind map. Once the host type is finalized, depending on number of server below option could be selected for ESXi installation:

Desktop Virtualization and VMware Horizon View basics

What is Desktop Virtualization ?

Like in server virtualization, Operating system is abstracted from the physical hardware and hardware resource like CPU and Memory can be distributed to multiple Operating Systems, similarly in Desktop Virtualization, the desktop operating system like Windows 7 or Windows 8 are virtualized and centrally managed. These Virtualized desktops are accessed through client (plugin), which can be installed on any endpoints like Desktop, Laptop, thin client, zero client, tabs, mobile running any OS like Windows, iOS, Android or Linux. This gives lot of flexibility for users to work from anywhere, anytime and through any device without compromising on company security as the complete virtualized desktops are centrally managed. All the policies can be applied on desktops or groups of desktops and you decide what users see on their desktops.

Similarly Application Virtualization is abstraction of application from operating system. Vmware ThinApp encapsulates application and further it can streamed or published to any Virtual Desktop. One of the best application I can think of is running IE6 on Windows 7.

Currently there are two major competitors Vmware Horizon View/ThinApp and Citrix Xendesktop/ XenApp, both are leaders in magic quadrant. Other Desktop virtualization solutions include MS VDI and Redhat VDI. Everyone has different approach to achieve the same outcome, few are complex to setup and complex to use. I will try to cover the basic architecture of Vmware Horizon View for desktop virtualization

There are lot of components involved to achieve complete desktop virtualization solution, I will just touch base to setup normal desktop virtualization with minimum components. The Desktop Virtualization infrastructure sits on top of server virtualization (ESXi hosts and vCenter). The Connection server interacts with vCenter Server to deploy any virtual desktop through templates or linked clones (VMware composer). These desktop images (template) needs to have view agent, and the end points(laptop, thin client, ipad etc) needs to have a view client.

Components Description:

vSphere ESXi - Host to run Virtual Desktops or other virtual machines.

vCenter Server - Management software to manage all ESXi hosts and Virtual Machines.

Connection Server (View Manager) - Broker, which provisions desktops on ESXi hosts through vCenter Server. It connects the end users to their respective virtual desktops.

ThinApp - Application virtualization, applications could be streamed separately along with Virtual Desktops

VMware composer - Works along with connection server & vCenter Server and with the help linked clone create multiple  virtual desktops in minutes.

I hope the post was helpful in understanding the basics of desktop virtualization and basic understanding of VMware horizon view architecture.

Vcenter Server - Basics

In the previous blog, we were talking about Server Virtualization, which allows us to run multiple Virtual Machines on it. Total number of Virtual Machines which can run on a single Physical Server depends on size of the Virtual Machine and Physical resources (CPU and Memory) on the Physical Server. If the Physical Server goes down, that will fail all the running Virtual Machines.

Even I have seen some customers who just Install ESXi and run plenty of critical Virtual Servers on it and say they are on Virtualization. I tell them, they are on Virtualization but with risk!!! If the physical server fails, they will lose access to Running Virtual Machine. Just Virtualizing is like utilizing 10% benefits of Virtualization. Now, to address these multiple Virtual Machines Failure, there is Management software called vCenter Server.

vCenter Server is installed on Windows Server Operating system like server 2008 R2 and it manages all the hosts and Virtual Machines from one place. It is just not used for managing all the Virtualized Servers and hosts, it provides various distributed Services like vMotion, HA, DRS, FT etc.

People who do not like vCenter Server on Windows, they can deploy vCenter Server Appliance (SUSE Linux based), it is preconfigured with Database and Services like Single Sign On, Inventory services. There is no difference in functionality just that one is running on Windows platform and other on Linux.

A database is mandatory for vCenter Server, the embedded Database which comes with vCenter Server is suitable for 5 Hosts and 50 Virtual Machines on Windows Platform and for vCenter Server Appliance (vCSA 5.5) it supports upto 500 Hosts and 5000 Virtual Machines, for any environment bigger than 5 Hosts and 50 Virtual Machines, a full blown Database is mandatory.

I will talk about all the distributed feature what vCenter Server provides in next blogs and watch out for lab section for deployment of ESXi 5.5 and vCenter Server Appliance 5.5. There is lot to understand about vCenter Server and how it interacts with ESXi hosts and Virtual Machines, which I will cover in other blog. 

What is Virtualization

I just added new section to my blog where I will try to cover concepts of various Vmware products, their architecture and how the product works. I will start from Vmware Hypervisor and then to more complex products like vCloud Director, so that anyone who is new to Virtualization can also get an idea about how exactly Virtualization works. So, let's start with Vmware hypervisor

Before we get into Virtualization, let me brief you about Vmware offering. There are two types of Virtualizations

1. Hosted Virtualization
2. Datacenter / Bare-Metal Virtualization

Hosted Virtualization: Here you are running Virtual Machines on top of regular Operating System, like Windows Vista, Windows 7 / 8 etc. So, a software is installed on normal operating system and with help of that software, VMs can be created and most of the product features can be experienced. Vmware has a product called "Vmware Workstation 10" for Windows and Fusion 6 for Mac Desktops. This is how Workstation looks with some Virtual Machines on it. Very simple and very useful for Lab and Demo purpose.

Datacenter / Bare-Metal Virtualization: You can say it is the Hypervisor layer or Operating System which is directly installed on the physical server and runs the Virtual Machines directly on top of it. Even physical machines can be converted to Virtual Machines with the help of software (like Vmware Converter) and run on this hypervisor. These Virtual Machines are same as Physical Machines but with more capabilities and more flexibilities. Many devices like Hard Drive, CD/DVD, Floppy devices can be added on fly. Also, Memory and CPU can be hot-added by enabling that feature.

Now, let's understand what exactly is Virtualization:

"It's an abstraction layer that masks the physical resources of hardware equipment to provide a system with resources that differ from what they actually are."

Normally when you install any operating system (like Server 2008 R2) on a physical server, all the physical resources are restricted to the same operating system and it is not fully utilized, you can always see there is lot of idle resource like CPU 12% utilized, but rest of 88% CPU is idle. Of course this would be used during spike but the spikes happen for limited time.

When you install Vmware ESXi (Hypervisor from Vmware), it masks the physical resources (cpu, memory) and provides new level of independence, where the resources can be distributed to multiple Virtual Machines. Below picture shows you the difference between Traditional server and a Virtualized server. All the Virtual Machines are getting the CPU, RAM, Network from the physical server and they are Virtual CPU (vCPU), Virtual RAM and Virtual Nic.

• Single physical server runs multiple Virtual Machines.
• Each Virtual Machine has its own applications running.
• Any Operating System can installed in a Virtual Machine.
• Virtual Machines can of different sizes, i.e., different configurations.

Server Consolidation is the major reason why companies Virtualize their environment. Multiple Servers can run as Virtual Machines on a single bigger physical server after installing Vmware ESXi on it.

I hope this was helpful to understand the definition of Virtualization. Before I end this introduction blog, I will leave you with one question, what happens if the physical server goes down due to some hardware failure, will it not fail all the Virtual Machines running on it ?