VMWare useful definations

Standard Edition: 1 vcenter server in standard license, Up to 2vCPU for FT, vMotion, Storage vMotion, HA, VVols etc.

Enterprise Edition: Same as Standard edition, additionally API's for Array Integration and multipathing DRS and DPM.

Enterprise Plus: Includes all features of Standard and Enterprise with additionally FT upto 4vCPU and 64GB RAM includes distributed vSwitch.

=> Max RAM support in vsphere 6.0 is 12TB

=> To move powered off VM from one host to another is called cold migration. 

=> To move powered on VM from one host to another is called vMotion.

=> Single cluster can manage max 8000 VMs

=> Single cluster can manage max 64 hosts in vsphere 6.0

=> Min 3 Esxi Hosts/Servers in the form of vSAN cluster require. If one of server fails vSAN cluster will fail.

=> Max 64 hosts are allowed to configure a vsan cluster.

=> A Host which has highest numbers of datastores mounted will be selected as a master host.

=> .vmx - Configuration file for a virtual machine

=> .nvram - BIOS related info of Virtual Machine

=> .vmdk - Virtual Machine Disk file and stores data of a Virtual Machine it can be up to 62TB in 6.0

=> vDS (Virtual Distributed Switch) 

- Single switch in whole virtual environment  and is responsible to provide central provisioning administration and monitoring of virtual network.

=> VSS (Virtual Standard Switch)

- For communication of virtual machines hosted on a single physical host.
- It works like a physical switch automatically detects a VM's which want to communicate with other VM on a same physical server.

=> VVol - (Virtual Volume)

- A new disk management concept introduced in vsphere 6.0 that enables array based operations at the virtual disk level. VVol is automatically  created when virtual disk is created in virtual environment for virtual machine.

=> vSAN (Virtual SAN)

- (I) Hybrid
- Uses both flash-based and magnatic disks for storage, Flash are used for caching while magnatic disks are used for capacity or storage.

- (II) All-Flash
- Uses flash for both caching and for storage.


=> VMKernal adapter

- VMKernel adapter provides network connectivity to the ESXi host to handle network traffic for vMotion, IP Storage, NAS, Fault Tolerance, and vSAN. For each type of traffic such as vMotion, vSAN etc. separate VMKernal adapter should be created and configured.

=> port groups

- You can segregate the network traffic by using port groups such as vMotion, FT, management traffic etc.

- Virtual Machine Port Group – Used for Virtual Machine Network

- Service Console Port Group – Used for Service Console Communications

- VMKernel Port Group – Used for VMotion, iSCSI, NFS Communications

=> Hypervisor -

- Hypervisor is a virtualization layer that enables multiple operating systems to share a single hardware host.  Each operating system or VM is allocated physical resources such as memory, CPU, storage etc by the host. There are two types of hypervisors.

- Hosted hypervisor (works as application i-e VMware Workstation)

- Bare-metal (is virtualization software i-e VMvisor, hyper-V which is installed directly onto the hardware and controls all physical resources).

=> VMware HA and FT

- Main difference between VMware HA and FT is: HA is enabled per cluster and VMware FT is enabled per VM. In HA, VMs will be re-started and powered-on on another host in case of host failure, while in FT there is no downtime, because second copy will be activated in case of host failure.

=> Disk Types

- There are three disk types in vSphere.

- Thick Provisioned Lazy Zeroes: every virtual disk is created by default in this disk format. Physical space is allocated to a VM when virtual disk is created. It can’t be converted to thin disk.

- Thick Provision Eager Zeroes: this disk type is used in VMware Fault Tolerance. All required disk space is allocated to a VM at time of creation. It takes more time to create a virtual disk compare to other disk formats.

- Thin provision: It provides on-demand allocation of disk space to a VM. When data size grows, the size of disk will grow. Storage capacity utilization can be up to 100% with thin provisioning.

=> VMware DRS

- DRS stands for Distributed Resource Scheduler; that automatically balances available resources among various hosts by using cluster or resource pools. With the help of HA, DRS can move VMs from one host to another to balance the available resources among VMs.

=> VMware Template

- When a VM is converted into a format which can be used to create a VM with pre-defined settings is called a template. An installed VM can be converted into a template but it cannot be powered-on.

=> Snapshot

- To create a copy of a VM with the time stamp as a restore point is called a snapshot. Snapshots are taken when an upgrade or software installation is required. For better performance, a snapshot should be removed after particular task is performed.

=> How to convert a physical machine into a VM?

- Three steps are required to convert a physical machine to a VM:

- An agent needs to be installed on the Physical machine

- VI client needs to be installed with Converter Plug-in

- A server to import/export virtual machines

=> What monitoring method is used in vSphere HA?

- Network Hearbeat

- Datastore Heartbeat

=> How master host is elected in vSphere HA?

- When HA is enabled in a cluster, all hosts take part in selection process to be selected as a master host. A host which has highest number of datastores mounted, will be selected as a master host. All other hosts will remain slave hosts.

=> VMware Tools

- It is a suite of utilities which are used to enhance performance of a VM in the form of graphics, mouse/keyboard movement, network card and other peripheral devices.

=> ESXi Shell

- It is a command-line interface is used to run repair and diagnostics of ESXi hosts. It can be accessed via DCUI, vCenter Server enable/disable, and via SSH.