Information Technology Reference
In-Depth Information
new infrastructure and the old one is being retired, it might also require shutdown for migra-
tion. But this can be done by sections, slowly, so downtime can be lessened.
Utilization Overutilization can cause adverse effects to a system. If the resources are
being exhausted or approaching their limits, it might cause inconsistencies in files such as
metadata and configuration files due to there not being enough resources to go around. In
these cases, some portions really have to be shut down and rebooted. Scalability mitigates
this, but in reality that benefit is only ideal and in practice. Especially in a pay-to-use model
where a client might not be financially capable of scaling yet, some utilization may have to
be dropped in order to stay within profitable margins.
Virtual Components of the Cloud
We have already discussed most of these components in the preceding sections and even in
the preceding chapters, so the following sections will count as a recap and summary of sorts.
Virtualization is the key to cloud computing despite most people saying that its heart lies
in the benefits and the functionalities. For us, the heart of any service or technology is the
infrastructure that supports it, for good reason. Without it, the functionalities cannot be
offered and the benefits cannot be achieved.
Virtual Network Components
Just as virtualization is at the heart of cloud computing, networking is the basis for delivery.
Without it, there is no way to deliver the benefits and functionalities.
Virtual NIC The virtual NIC is the logical equivalent of a physical network adapter and
was specifically designed to mimic and emulate its functions and inner workings. It allows
the virtual machine to be connected to a virtual network or to an external physical network
by binding to a physical NIC or connecting to a virtual switch bound to a physical NIC.
This is one of the most essential components in a virtualized system because it allows
communication between virtual components and the physical network, allowing the
virtual machines to truly become part of the infrastructure.
Virtual HBA When every facet of the data center (such as storage, servers, and storage
area networks) goes virtual due to cloud computing, so too must the interfaces that connect
them. The virtual host bus adapter is the logical equivalent of a host bus adapter used for
input/output processing and communication between servers and storage devices. Like the
physical HBA, the virtual one relieves the VM processor of I/O processing and facilitates
high-speed I/O communication between it and all connected logical unit numbers (LUNs)
and SANs.
With the virtualization of the HBA, it becomes easier to isolate parts of the network and
facilitate better management and traffic efficiency, preventing unwanted overall downtime
through virtual SANs.
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