Virtualization (III)

Server Virtualization

Out of all three of the different types of virtualization discussed in this blog, I believe that server virtualization is the type of virtualization everybody is most familiar with. When people say "virtualization", they are usually referring to server virtualization because this is the main area of virtualization, whereby a number of “virtual machines” are created on one server meaning that multiple tasks can then be assigned to the one server, saving on processing power, cost and space.

Server virtualization inserts a layer of abstraction between the physical server hardware and the software that runs on the server allowing us to run multiple guest computers on a single host computer with those guest computers believing they are running on their own hardware. The physical machine is translated into one or more virtual machines (VMs). Each VM runs its own operating system and applications, and each utilizes some allocated portion of the server's processing resources such as CPU, memory, network access and storage I/O. This means that any network tasks that are happening on the server still appear to be on a separate space, so that any errors can be diagnosed and fixed quickly.



By doing this, we gain all the benefits of any type of virtualization: portability of guest virtual machines, reduced operating costs, reduced administrative overhead, server consolidation, testing & training, disaster recovery benefits, and more.

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Virtualization (II)

Network Virtualization

When we think of network virtualization, we always think of VLANs but there is much more to network virtualization than just VLANs. Network virtualization is when all of the separate resources of a network are combined, allowing the administrator to share them out amongst the users of the network. Thus, it is a method of combining the available resources in a network by splitting up the available bandwidth into channels, each of which is independent from the others, and each of which can be assigned (or reassigned) to a particular server or device in real time. This allows each user to access all of the network resources from their computer either they are files and folders on the computer, printers or hard drives etc.



The theory behind network virtualization is to take many of the traditional client/server based services and put them "on the network". Certain vendors advertise virtualization and networking as a vehicle for additional services and not just as a way to aggregate and allocate network resources. For example, it's common practice for routers and switches to support security, storage, voice over IP (VoIP), mobility and application delivery.

One network vendor actually has a working card that is inserted into a router. On that card is a fully-functioning Linux server that has a connection to the backbone of the router. On that Linux server, you can install applications like packet sniffers, VoIP, security applications, and many more.
Network virtualization provides an abstraction layer that decouples physical network devices from operating systems, applications and services delivered over the network allowing them to run on a single server or for desktops to run as virtual machines in secure data centers, creating a more agile and efficient infrastructure. This streamlined approach makes the life of the network administrator much easier, and it makes the system seem much less complicated to the human eye than it really is.

Network virtualization is a versatile technology. It allows you to combine multiple networks into a single logical network, parcel a single network into multiple logical networks and even create software-only networks between virtual machines (VMs) on a physical server. Virtual networking typically starts with virtual network software, which is placed outside a virtual server (external) or inside a virtual server, depending on the size and type of the virtualization platform.

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Virtualization (I)

Virtualization is a massively growing aspect of computing and IT creating "virtually" an unlimited number of possibilities for system administrators. Virtualization has been around for many years in some form or the other, the trouble with it, is being able to understand the different types of virtualization, what they offer, and how they can help us.

Virtualization has been defined as the abstraction of computer resources or as a technique for hiding the physical characteristics of computing resources from the way in which other systems, applications, or end users interact with those resources. In fact, virtualization always means abstraction. We make something transparent by adding layers that handle translations, causing previously important aspects of a system to become moot.

Storage Virtualization

The amount of data organizations are creating and storing is rapidly increasing due to the shift of business processes to Web-based digital applications and this huge amount of data is causing problems for many of them. First, many applications generate more data than can be stored physically on a single server. Second, many applications, particularly Internet-based ones, have multiple machines that need to access the same data. Having all of the data sitting on one machine can create a bottleneck, not to mention presenting risk from the situation where many machines might be made inoperable if a single machine containing all the application’s data crashes. Finally, the increase in the number of machines causes backup problems because trying to create safe copies of data is a tremendous task when there are hundreds or even thousands of machines that need data backup.

For these reasons, data has moved into virtualization. Companies use centralized storage (virtualized storage) as a way of avoiding data access problems. Furthermore, moving to centralized data storage can help IT organizations reduce costs and improve data management efficiency. The basic premise of storage virtualization solutions is not new. Disk storage has long relied on partitioning to organize physical disk tracks and sectors into clusters, and then abstract clusters into logical drive partitions (e.g., the C: drive). This allows the operating system to read and write data to the local disks without regard to the physical location of individual bytes on the disk platters.
Storage virtualization creates a layer of abstraction between the operating system and the physical disks used for data storage. The virtualized storage is then location-independent, which can enable more efficient use and better storage management. For example, the storage virtualization software or device creates a logical space, and then manages metadata that establishes a map between the logical space and the physical disk space. The creation of logical space allows a virtualization platform to present storage volumes that can be created and changed with little regard for the underlying disks.



The storage virtualization layer is where the resources of many different storage devices are pooled so that it looks like they are all one big container of storage. This is then managed by a central system that makes it all look much simpler to the network administrators. This is also a great way to monitor resources, as you can then see exactly how much you have left at a given time giving much less hassle when it comes to backups etc.

In most data centers, only a small percentage of storage is used because, even with a SAN, one has to allocate a full disk logical unit number (LUN) to the server (or servers) attaching to that LUN. Imagine that a LUN fills up but there is disk space available on another LUN. It is very difficult to take disk space away from one LUN and give it to another LUN. Plus, it is very difficult to mix and match storage and make it appear all as one.
 

Storage virtualization works great for mirroring traffic across a WAN and for migrating LUNs from one disk array to another without downtime. With some types of storage virtualization, for instance, you can forget about where you have allocated data, because migrating it somewhere else is much simpler. In fact, many systems will migrate data based on utilization to optimize performance.

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