Learn about virtual systems, virtual storage, virtual networking,
and the benefits of virtualizing these resources.
Virtualization is the creation of substitutes for real resources,
that is, substitutes that have the same functions and external interfaces
as their counterparts, but that differ in attributes, such as size,
performance, and cost. These substitutes are called virtual
resources, and their users are typically unaware of the substitution.
Virtualization is commonly applied to physical hardware resources
by combining multiple physical resources into shared pools from which
users receive virtual resources. With virtualization, you can make
one physical resource look like multiple virtual resources. Virtual
resources can have functions or features that are not available in
their underlying physical resources.
Virtualization can provide the following benefits:
- Consolidation to reduce hardware cost
- You can use virtualization to efficiently access and manage resources
to reduce operations and systems management costs while maintaining
needed capacity.
- You can use virtualization to have a single server function as
multiple virtual servers.
- Optimization of workloads
- You can use virtualization to respond dynamically to the application
needs of its users.
- You can use virtualization to increase the use of existing resources
by enabling dynamic sharing of resource pools.
- IT flexibility and responsiveness
- You can use virtualization to have a single, consolidated view
of, and easy access to, all available resources in the network, regardless
of location.
- You can use virtualization to reduce the management of your environment
by providing emulation for compatibility and improved interoperability.
When you think about applying virtualization to your current environment,
you must think about consolidating logical resources rather than physical
resources into a system designed to support server, storage, and network
virtualization. By adding any of these virtualization technologies
to your environment, you create an on demand, secure, and flexible
infrastructure prepared to handle workload changes in your environment.
Virtual systems
System virtualization creates
many virtual systems within a single physical system. Virtual
systems are independent operating environments that use virtual
resources. System virtualization can be approached through hardware
partitioning or hypervisor technology. Hardware partitioning subdivides
a physical server into fractions, each of which can run an operating
system. These fractions are typically created with coarse units of
allocation, such as whole processors or physical boards. This type
of virtualization allows for hardware consolidation, but does not
have the full benefits of resource sharing and emulation offered by
hypervisors. Hypervisors use a thin layer of code in
software or firmware to achieve fine-grained, dynamic resource sharing.
Because hypervisors provide the greatest level of flexibility in how
virtual resources are defined and managed, they are the primary technology
for system virtualization.
System virtualization yields the
following benefits:
- Consolidate systems, workloads, and operating environments:
- Multiple workloads and operating systems can be combined onto
one physical server, reducing the costs of hardware and operations.
- New versions of software can be tested on the hardware that they
will later use in production mode without affecting production workloads.
- Virtual systems can be used as low-cost test systems without jeopardizing
production workloads.
- Multiple operating system types and releases can run on a single
system. Each virtual system can run the operating system that best
matches its application or user requirements.
- Optimize resource use:
- Hypervisors can achieve high resource use by dynamically assigning
virtual resources (such as processors and memory) to physical resources
through mechanisms such as dispatching and paging. The virtual resources
that they provide can exceed the physical system resources in quantity
and functionality.
- With system virtualization, you can dynamically share physical
resources and resource pools. This results in higher resource use,
especially for variable workloads whose average needs are much less
than an entire dedicated resource.
- Different workloads tend to show peak resource use at different
times of the day and week, so implementing multiple workloads in the
same physical server can improve system use, price, and performance.
- Improve IT flexibility and responsiveness:
- Service providers can create one virtual system or clone many
virtual systems on demand, achieving dynamic resource provisioning.
- Virtual systems with variable resources enable the manual or automated
management of workload resources.
Virtual storage
Virtual storage technology
allows multiple logical partitions to share storage adapters and devices.
Virtual SCSI adapters interact with the operating system like any
other adapter, except that they are not physically present. A logical
partition can use virtual SCSI to connect to a hard disk drive or
optical device that is shared by multiple logical partitions on the
system.
A logical partition can use virtual fibre channel to communicate
with storage devices in a storage area network (SAN). Configuring
this type of storage resource is available when a system
supports the use of virtual fibre channel adapters and has a physical
fibre channel adapter installed and connected that supports N_Port
ID Virtualization (NPIV) ports.
Virtual networking
Network virtualization
is the ability to manage and prioritize traffic in portions of a network
that might be shared among different enterprises. This ability allows
administrators to use performance, resources, availability, and security
more efficiently. The following virtualization technologies primarily
exist at the system level and require hypervisor and Licensed Internal
Code support to enable sharing between different operating systems:
- Virtual IP address takeover
- The assignment of a virtual IP address to an existing interface.
If one system becomes unavailable, virtual IP address takeover allows
for automatic recovery of network connections between different servers.
- Virtual Ethernet
- With this technology, you can use internal TCP/IP communication
between partitions.
- virtual LAN (VLAN)
- A logically independent network. Several virtual LANs can exist
on a single physical switch.
- virtual private network (VPN)
- An extension of a company's intranet over the existing framework
of either a public or private network. A VPN ensures that the data
that is sent between the two endpoints of its connection remains secure.
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