Database Reference
In-Depth Information
the hypervisor that provide for high availability. As discussed in
Chapter 6
,
“
Architecting for Performance: Storage
,
” the storage stack has been built to seamlessly
and transparently handle hardware failure. If one of the HBA cards in your ESXi host
fails, I/O operations are automatically routed out another HBA card. If a path to the
storage array becomes inaccessible, the hypervisor will reroute the I/O down another
path to the array. In addition, to handle situations in which there is an overallocation of
storage resources, vSphere will leverage storage I/O control to ensure proper
distribution of I/O to the virtual machines. Review
Chapter 6
for more information on
these features.
Chapter 8
,
“
Architecting for Performance: Network
,
” discusses the networking high
availability VMware has built in to their networking stack. The vSphere distributed
switch removes the complexity of manually configuring each individual virtual switch
on every ESXi host. Let's face it, having to do something manually over and over opens
the door for errors. One central location to manage a configuration and have this
configuration remotely applied reduces errors and makes the environment more
available by reducing downtime due to administrative error.
Much like storage I/O, VMware introduced network I/O control into the vSphere stack
to ensure the delivery of critical network services—for example, NFS and iSCSI
performance when a vMotion is initiated, and proper distribution of network bandwidth
when an overallocation of network resources occurs on a physical network card. Just as
important as availability is performance. The phone rings whether the system is slow or
if the system is down, so leverage technologies built in to vSphere to ensure
performance for virtual machines. Read
Chapter 8
for more information on these and
other features within the vSphere hypervisor that will allow you to architect a
performant (yes, there is that word again) and highly available network stack.
The previous storage and network examples are just a few of the built-in features of the
hypervisor. We will now move on to discussing configurable features within the
hypervisor and the vSphere platform.
vMotion
Do you remember your first vMotion? I sure do. There are few things in our lives that
we remember exactly when and where we were when they occurred. Throughout our
travels, one question that always gets a resounding “yes” is when we ask about people's
first vMotion moment. vMotion provides the ability to migrate (move) a powered-on
virtual machine from one physical host to another physical host with no downtime or
interruption to the services provided by that virtual machine.
Memory Lane
My first vMotion moment occurred in a data center in Akron, Ohio. My VMware
