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McCain c01.tex V3 - 09/17/2009 12:23pm Page 6
6 CHAPTER 1 INTRODUCING VMWARE VSPHERE 4
Chapter 4, ‘‘Installing and Configuring vCenter Update Manager,’’ features more extensive
coverage of vCenter Update Manager.
VMware vSphere Client
The VMware vSphere Client is a Windows-based application that allows you to manage ESX/ESXi
hosts, either directly or through a vCenter Server. You can install the vSphere Client by browsing
to the URL of an ESX/ESXi host or vCenter Server and selecting the appropriate installation link.
The vSphere Client is a graphical user interface (GUI) used for all the day-to-day management
tasks and for the advanced configuration of a virtual infrastructure. Using the client to connect
directly to an ESX/ESXi host requires that you use a user account residing on that host, while
using the client to connect to a vCenter Server requires that you use a Windows account. Figure 1.3
shows the account authenticationforeachconnectiontype.
Figure 1.3
The vSphere Client
manages an individ-
ual ESX/ESXi host by
authenticating with an
account local to that
host; however, it man-
ages an entire enterprise
by authenticating to a
vCenter Server using a
Windows account.
ESX/ESXi
DRS HA
VCBVMotlon
Virtual Center
ESX/ESXi
Almost all the management tasks available when you’re connected directly to an ESX/ESXi
host are available when you’re connected to a vCenter Server, but the opposite is not true. The
management capabilities available through a vCenter Server are more significant and outnumber
the capabilities of connecting directly to an ESX/ESXi host.
VMware VMotion and Storage VMotion
If you have read anything about VMware, you have most likely read about the extremely unique
and innovative feature called VMotion. VMotion, also known as live migration, is a feature of
ESX/ESXi and vCenter Server that allows a running virtual machine to be moved from one phys-
ical host to another physical host without having to power off the virtual machine. This migration
between two physical hosts occurs with no downtime and with no loss of network connectivity to
the virtual machine.
VMotion satisfies an organization’s need for maintaining SLAs that guarantee server availabil-
ity. Administrators can easily initiate VMotion to remove all virtual machines from an ESX/ESXi
host that is to undergo scheduled maintenance. After the maintenance is complete and the server
is brought back online, VMotion can again be utilized to return the virtual machines to the original
server.
Even in normal day-to-day operations, VMotion can be used when multiple virtual machines
on the same host are in contention for the same resource (which ultimately is causing poor
performance across all the virtual machines). VMotion can solve the problem by allowing an
administrator to migrate any of the running virtual machines that are facing contention to another
ESX/ESXi host with greater availability for the resource in demand. For example, when two vir-
tual machines are in contention with each other for CPU power, an administrator can eliminate
the contention by performing a VMotion of one of the virtual machines to an ESX/ESXi host that