Virtualisation is evolving. IT departments now have a raft of products to deploy within their infrastructure, optimised for virtualisation.
For years, network topology was defined by the physical connections between network devices. If you wanted two servers to be in the same network domain, they needed to be on the same switch. Today, network hardware is being completely transformed into virtual hardware that exists only within the realm of Linux KVM, Microsoft Hyper-V, or VMware.
Cisco, for example, has released the Nexus 1000v, a virtual Cisco switch that runs within VMware environments, but is managed by traditional Cisco management tools.
Virtual network infrastructure performs the same job as its physical counterpart, except that all network traffic remains inside the virtual server environment until it needs to talk to something in the “real” world. Virtualised network traffic moves between virtual servers at memory speeds, since there are no physical limitations such as 100MB copper networks. And because the infrastructure is virtual, new gear and virtual wiring can be created instantly.
Companies such as Cisco, Citrix and F5 offer a number of network-resident products that offload tasks from servers or optimise network traffic. Instead of offloading just one task, these products typically consolidate a broad array of capabilities that can include connection request handling, caching, SSL encryption co-processing, compression, and packet flow control. In addition to decreasing application response times, network performance virtualisation reduces the amount of infrastructure required to deliver an application and can support consolidation/centralisation initiatives by saving on server and bandwidth resources.
Stages of virtualisation evolution
- The very first commercial and open source products hit the market
- Initial production environment deployments take place
- Ecosystem expands to include suppliers, customers, and enablers such as systems integrators
- Leading-edge customers and end users begin to share their experiences with the product
- Suppliers compete to earn plaudits and early customer wins
Network equipment suppliers have had to rethink their architecture to adapt to shifts such as the scale-out computing and composite applications that use web services to speak to each other. These trends are driving the need for a network that can scale to very large numbers of ports while adapting to the increase in application-to-application (also called east-west) traffic that runs counter to traditional designs that favour client-to-server communications (or north-south traffic).
Chassis virtualisation allows firms to build networks that are simpler and more predictable by reducing the number of tiers required to aggregate traffic into a small number of core switches. In addition, management is greatly simplified because switches behave as if they are part of a much larger virtual switch. Being part of a single virtual switch also permits a group of switches to make decisions collectively, rather as independent nodes that lack the complete picture.
Security has been deployed at the network perimeter for many years, but changing business and application requirements have made pervasive security a requirement. This shift forced operations to deal with a highly distributed network of security tools that still needed to be inserted into the network at the right control points. Network security virtualisation is changing that by making security available as a service on your network, so you don’t have to purchase and install another box every time you need to firewall a new application server or provide secure remote access.
Storage virtualisation based on out-of-band technologies such as EMC’s Invista does not sit in the data flow. Rather, the virtualisation intelligence lives in a network-resident controller that instructs the storage infrastructure where to place data. Like most storage virtualisation today, out-of-band technologies are focused on improving utilisation, migration and management.
Virtual appliances have seen new interest because they provide an efficient way to rapidly start up a pre-configured server environment
Virtual servers from suppliers such as Citrix, Microsoft and VMware store their files on virtual disks. In reality, these virtual disks are simply large files that contain the image of an entire server. These virtual disks evolved into more sophisticated appliances based on standards such as Open virtualisation Format (OVF) that are capable of bundling multiple virtual machines along with information such as their network configuration and start-up sequences.
Software suppliers have noticed that virtual disks allow them to ship their products in a fully configured and tested virtual machine. This is similar to a physical appliance in that you, the customer, don’t have to do anything but start it up. As cloud computing has gained acceptance, virtual appliances have seen new interest because they provide an efficient way to rapidly start up a pre-configured server environment.
While virtual machine (VM) management is necessary for day-to-day server operations, virtualised environments have expanded the use of policy-based intelligence that can balance workloads or respond to failures.
Forrester previously labelled these capabilities as "VM automation", which was focused on optimising a relatively simple virtual server environment. But as cloud computing has emerged, these same capabilities have expanded to include important cloud capabilities such as:
- Managing resources across multiple pools;
- Optimising cost and service leval agreements (SLAs) using public and private resources;
- Offering self-service interfaces and virtualised resource models that simplify management and provide multi-tenancy.
We believe that even firms that don’t plan to deploy a private cloud will make use of basic cloud management capabilities such as automated workload management.
Hypervisors are the core technology in server virtualisation, although the concept of virtual machines dates back to the mainframe and later Unix-based systems from HP, IBM and Oracle Sun. Hypervisors from companies such as Citrix, Microsoft and VMware are critical because they are now bringing the same benefits to commodity x86 servers running Windows and Linux.
As virtualisation specialists such as VMware have reduced the size of the hypervisor, major server suppliers are shipping new x86 systems that have a hypervisor already loaded in flash memory.
As hypervisors mature, more and more emphasis is being placed on the software that controls them. Virtualisation management tools govern the basic provisioning, movement and performance of virtual servers, networks and storage. The growth in server virtualisation adoption and the increasing number of virtualisation options from the likes of Citrix, Microsoft, Oracle, Red Hat and VMware has created a need for tools that offer heterogeneous management for virtual infrastructure.
This article is based on Forrester's “TechRadar for enterprise architecture professionals infrastructure virtualization, Q2 2011” report (May, 2011) by Galen Schreck.
Schreck is vice-president and principal analyst at Forrester, serving enterprise architecture professionals. His blog can be found at: http://blogs.forrester.com/galen_schreck.