Virtualization according to VMware began in the 1960s, when IBM attempted to better partition mainframe computers with the goal to increase CPU utilization. The result was a mainframe that could perform multiple operations simultaneously. There was another concept known as insufficient utilization. With many implementations of the x86 architecture, the average CPU utilization was between 10 to 15 % of the total capacity. The primary reason was the practice of running one server per CPU to increase the performance of a server individually.
Virtualization Advantages: undoubtedly virtualization has become widely popular in the IT industry. The reason being is the increased CPU utilization increased space utilization, and build the standardize servers architecture. Regarding the CPU utilization, the more the servers are on one single machine typically translates into more work performed by the CPU. Rather than receiving all web traffic on one machine, all SMTP traffic on another machine, and all FTP traffic on another, it is possible to receive all the traffic on one single machine, thereby increasing the CPU utilization. However, this involves some discretion in some virtual machines on one host machine and has the potential to decrease performance.
CPU utilization provided by the virtualization affects space utilization also. As per the above scenario where multiple servers are hosted on a single server, it stands to reason that with virtualization, fewer machines are needed and hence less space is consumed.
Finally, the virtualization lends the other concepts of clones, ghosting, snapshots and any replicating software available. The value provides a system administrator by creating images of any operating system on the network. Creating custom images allows the system administrator to replicate throughout the network.
Disadvantages of Virtualization: The majority is the issue about the virtualization is the security. The most dominant disadvantage is the concept of a single point of failure. Let us brief this a bit more here, supposedly an organization’s web servers, SMTP server, database server are hosted on the same physical machine then a hacker has only to perform a denial of service attack on that host machine to disable multiple servers within the whole network infrastructure.
Secondly, a common security practice is intrusion detection system on multiple network interfaces within the network. When installed correctly helps in studying trends, heuristics, and other activities within the whole network. Thus it is impossible in the virtualized environment where multiple operating systems are placed on the host machine due to the intrusion detection system which is capable of monitoring network interfaces.