Information Technology Reference
In-Depth Information
The choice of which block protocol should be used to support the VMFS and RDM use cases
depends on the enterprise more than the technologies and tends to follow this pattern:
iSCSI for customers who have never used and have no existing Fibre Channel SAN
infrastructure
◆
Fibre Channel for those with existing Fibre Channel SAN infrastructure that meets their
needs
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FCoE for those upgrading existing Fibre Channel SAN infrastructure
◆
vSphere can be applied to a very broad set of use cases—from the desktop/laptop to the
server and on the server workloads—ranging from test and development to heavy workloads
and mission-critical applications. A simple one-size-i ts-all model can work, but only for the
simplest deployments. The advantage of vSphere is that all protocols and all models are sup-
ported. Becoming i xated on one model means that not everything is virtualized that can be and
the enterprise isn't as l exible and efi cient as it can be.
Now that you've learned about the basic principles of shared storage and determined how
to make the basic storage choices for your environment, it's time to see how these are applied in
vSphere.
Implementing vSphere Storage Fundamentals
This part of the chapter examines how the shared storage technologies covered previously
are applied in vSphere. We will cover these elements in a logical sequence, starting with core
vSphere storage concepts. Next, we'll cover the storage options in vSphere for datastores to
contain groups of VMs (VMFS datastores and NFS datastores). We'll follow that discussion
with options for presenting disk devices directly into VMs (raw device mappings). Finally, we'll
examine VM-level storage coni guration details.
Reviewing Core vSphere Storage Concepts
One of the core concepts of virtualization is encapsulation. What used to be a physical system
is encapsulated by vSphere, resulting in VMs that are represented by a set of i les. Chapter 9,
“Creating and Managing Virtual Machines,” provides more detail on the specii c i les that com-
pose a VM and their purpose. For reasons we've described already, these VM i les reside on the
shared storage infrastructure (with the exception of a raw device mapping, or RDM, which we'll
discuss shortly).
In general, vSphere uses a shared-everything storage model. All ESXi hosts in a vSphere envi-
ronment use commonly accessed storage objects using block storage protocols (Fibre Channel,
FCoE, or iSCSI, in which case the storage objects are LUNs) or network attached storage protocols
(NFS, in which case the storage objects are NFS exports). Depending on the environment, these
storage objects will be exposed to the majority of your ESXi hosts, although not necessarily to all
ESXi hosts in the environment. In Chapter 7, we'll again review the concept of a cluster, which is a
key part of features like vSphere HA and vSphere DRS. Within a cluster, you'll want to ensure that
all ESXi hosts have visibility and access to the same set of storage objects.
Before we get into the details of how to coni gure the various storage objects in vSphere, we
need to i rst review some core vSphere storage technologies, concepts, and terminology. This
