OFF TOPIC
Improving disaster recovery and business continuity with server virtualisation
Alberto Tinazzi IT Security Consultant eHealth Security Services
atinazzi@ehealthsecurity.com.au
What is virtualisation? Virtualisation is a technique that allows the user to run multiple instances of an operating system on a single physical computer. Physical resources such as CPU cores, memory, and storage of the single computer are subdivided amongst multiple ‘virtual’ machines. A common error is to confuse virtualisation with
emulation. An emulator mimics the behaviour of different hardware, for example, a computer with a typical Intel x86 CPU can emulate a PDA or a mobile phone based on an ARM CPU. Virtualisation instead relies on a piece of software called a hypervisor (or Virtual Machine Manager) which is responsible for allocating resources provided by a physical machine to a number of virtual machines compatible with the same type of hardware architecture. Many also confuse virtualisation with cloud
computing; however, while virtualisation is an enabling technology for many cloud computing platforms, cloud computing is concerned with providing computing resources as a service, in a timely, flexible and automated fashion. Virtualisation technology can be used on a
standard desktop computer when a user requires the ability to run multiple operating systems on a single desktop. In this scenario, virtualisation allows the user to run multiple operating systems conveniently, simultaneously, and without the need to set up complex disk partitioning and dual booting arrangements. For example, a Windows computer with VMware Workstation installed can run Linux on top of
Alberto Tinazzi is a Certified Information Systems Security Professional (CISSP). He works as an independent information security consultant specialised in the healthcare sector. He has 16 years experience as an IT professional, specialised in information management and security. He has spent the last 10 years working within the health sector covering a number of different roles within the Division of General Practice Network.
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Windows. Similarly, a Macintosh computer can use Parallels Desktop to run Windows on top of Mac OS X. Virtualisation also allows for standardised desktop
computer arrangements across an organisation, which can help to simplify management and increase security. This is called Virtual Desktop Infrastructure, and it consists of replacing all desktop PCs with thin clients connected through the local network to a large server running virtual instances of the desktop operating system and applications. Applications, drivers and updates can be installed just once, lowering the time required for the IT department to manage the infrastructure. Additional benefits introduced by this technology include: • Increased security, as all data is centralised. • A consistent user experience, as the user will have the same desktop view from any location in the organisation, including when connecting remotely. • Reduced total cost of ownership.
Server virtualisation The most widely-cast virtualisation technique, and probably the one that provides more immediate benefits from a business perspective, is server virtualisation. The rationale behind server virtualisation leverages the fact that a typical server CPU generally operates at between 5% and 15% of its capacity, meaning the server is more often than not heavily underutilised.1 Large organisations have been early adopters
of virtualisation, and have for many years been consolidating their server resources. Accordingly, despite the increasing computerisation of many organisations, the number of physical servers within organisations is reducing. A consolidation ratio of 4:1 means that four physical servers can be virtualised to run on one physical server, but there are cases where this ratio can be as high as 12:1. This provides a number of immediate tangible economical benefits, such as
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