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ESXi is the hypervisor in a vSphere environment. The hypervisor is installed on physical or virtual
hardware in a virtualized data center, and acts as a platform for virtual machines. The hypervisor provides
physical hardware resources dynamically to virtual machines to support the operation of the virtual
machines. The hypervisor allows virtual machines to operate with a degree of independence from the
underlying physical hardware. For example, a virtual machine can be moved from one physical host to
another, or its virtual disks can be moved from one type of storage to another, without affecting the
functioning of the virtual machine.
Because virtual machines are decoupled from the underlying physical hardware, virtualization allows you
to consolidate physical computing resources such as CPUs, memory, storage, and networking into pools
of resources. These resources can be dynamically and flexibly made available to virtual machines. With
the vCenter Server management platform, you can increase the availability and security of your virtual
infrastructure.
Physical Topology of vSphere Data Center
A typical VMware vSphere data center consists of physical building blocks such as x86 virtualization
servers, storage networks and arrays, IP networks, a management server, and desktop clients.
The vSphere data center includes the following components.
ESXi Hosts Industry standard x86 servers that run ESXi on the bare metal. ESXi
software provides resources for and runs the virtual machines. You can
group a number of similarly configured x86 servers with connections to the
same network and storage subsystems. This grouping creates an
aggregate set of resources in the virtual environment, called a cluster.
Storage networks and
arrays
VMware vSphere uses Fibre Channel SAN arrays, iSCSI SAN arrays, and
NAS arrays to meet different data center storage needs. With storage area
networks, you can connect and share storage arrays between groups of
servers. This arrangement allows aggregation of the storage resources and
provides more flexibility in provisioning them to virtual machines.
IP networks Each compute server can have multiple physical network adapters to
provide high bandwidth and reliable networking to the entire VMware
vSphere data center.
vCenter Server vCenter Server provides a single point of control to the data center. It
provides essential data center services such as access control,
performance monitoring, and configuration. It unifies the resources from the
individual computing servers to be shared among virtual machines in the
entire data center. It manages the assignment of virtual machines to the
ESXi hosts and the assignment of resources to the virtual machines within
a given computing server. These assignments are based on the policies
that the system administrator sets.
vCenter Server and Host Management
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