Understanding the Linux Virtual Memory Manager, Research Paper Example

Abstract

Virtualization managers are used to support applications execution.  In the early institution of operating systems the application was loaded into the physical memory of the computer and ran on that memory system. Virtual memory management allows for multiple applications running simultaneously, management of the physical memory as well as the enhanced capacity and utilization of the memory by swapping resource allocations.  The overall purpose of virtualization is to increase capability, capacity and efficiency of the use of the physical memory by allocating resources, taking advantage of fragmented memory and simplifies the organization of the application and data.  This is accomplished by establishing virtual memory addresses that are mapped to the physical locations of the application’s data.  Modern computer architecture utilizes virtual memory management as an integral part of hardware support and design.  The benefits of virtual memory management range from protecting applications from interfering with each other’s processes, creating the ability to share resources and simultaneous access to memory.

Virtualization

Virtualization of hardware and software allow for increased performance, productivity and resource utilization. Virtualization is the act or process of creating a virtual version of either hardware or software. Within businesses, the IT infrastructure is becoming more complex and critical for transactions, storage and productivity.  With the criticality increasing and the need to leverage current resources and decrease overhead costs for capital and operating equipment, virtualization of hardware and software can provide the advantage organizations need to remain competitive (Saxena & Swift, 2010).  The hardware virtualization is highly used with servers in which data is stored and retrieved.  Prior to virtualization, applications would run on dedicated servers that were not fully utilized.  The remaining capacity of the server would sit stagnant and would not be able to provide the full return on investment the organization is expecting. With the virtualization of the hardware, the host server, or machine, is virtualized which allows for guest machines to run. There are essentially three ways to virtualize hardware which includes full, partial or para-virtualization.  All three are variants of virtualization and each has their own positives and negatives regarding implementation and utilization.  The primary objective of the virtualization is to improve effectiveness and efficiency of the hardware by taking advantage of the physical attributes and processing power.  Another aspect of virtualization of hardware is the ability to run parallel operating systems while also maintaining the ever important factors of scalability.

Along with hardware virtualization, there is software virtualization.  Software virtualization is similar in nature to desktop virtualization.  Desktop virtualization is becoming another way to limit cost by organizations but also provide the tools and capability the employees need to do their job.  The concept is similar to hardware virtualization in that it is separating the host machine from the virtual machines and the concept also leverages off of the ability to utilize resources that would normally remain dormant.  The software or desktop virtualization allows users to access software applications through a virtual machine.  These machines normally are just screens, keyboards and mice.  The computer or CPU is housed in a separate location and handles all of the storage and processing that the end user would need.  This eliminates the need for personal computers or laptops for every end user.  These benefits fall into different areas that allow for increased capacity, colocation of applications, simultaneous utilization and overall efficiency. The ability to share and fully utilize the computer’s capability also allowed for multitasking of those resources. As organizations realign and merge their data systems, the ability to access and store information in a centralized location promotes the use of virtual hardware and software solutions.

Benefits

Hardware virtualization has a multitude of benefits.  One of the major cost drivers of implementing new capability or enhancing current capabilities is the cost of hardware.  Virtualization reduces the amount of hardware required to achieve the same results.  The reduction in the cost of hardware is a major driver but is not the total cost of ownership when it comes to the cost of ownership.  With the reduction of hardware, the cost is reduced by minimizing downtime, decreased maintenance, reduction in energy consumption and overall support for the capital equipment.  The hardware virtualization also promotes the ability to redeploy if there is a failure.  During the normal course of action, if a physical server goes down there is a high degree of impact to the organization and that impact, as well as the resulting return to service timeline, all depends on multiple variables.  If the server was not backed up recently there is a risk of data loss.  This could be a critical loss to business.  With the hardware virtualization, snapshots can be taken at specified timeframes and redeployment could occur within minutes with limited or no impact to the end users.  Maintaining service levels, within the organization as well as externally to outside users, is a key performance metric used bymany information technology teams (Gorman, 2004).  Along with maintaining service levels, there is a larger scale issue that is mitigated through virtualization of hardware. The ability to perform disaster recovery actions is accomplished through leveraging the key capability of virtualization and enabling the failover capability of the data center to be decentralized from potential hazards. Virtualization provides the flexibility needed to enable a disaster recovery plan with minimal impact to the organization.

With software virtualization, the increased capability and accessibility of software is the immediate benefit.  The full utilization of the virtualized servers allow the ability to leverage multiple applications on one server while also allowing the ability to scale users for the application based upon the business needs.  Just as the benefit for uptime and availability is critical for hardware utilization, the same holds true for software virtualization.  The ability to access and use software applications is a critical component to business operations. The ability to maintain availability and reliability falls into the category of key metrics that is measured by the information technology organization.  Along with the increased efficiencies and potential improvement of effectiveness of employees and IT resources there is also the benefit of consolidating resources.  This consolidation can eliminate costs by removing unneeded licenses, underutilized programs and redeploying critical resources to the appropriate areas within the organization.

Virtualization Solutions

VMWare, Microsoft and Citrix all offer virtualization opportunities.  VMWare is a well-established virtualization solution. The primary focus of VMWare spans across infrastructure and application services. VMWare is essentially scalable on the amount and type of virtualization that is required by the organization.  The main benefit of VMWare is the technical expertise and experience that is associated with the VMWare product (VMWare, 2014).  Microsoft’s Hyper-V virtualization works on a unified set of tools specific to Microsoft. They also leverage three environments from one console including physical, cloud and virtual. Microsoft’s focuses on unlimited datacenter virtualization based on a per-processor basis. Citrix also provides the ability to virtualize hardware and software but their primary focus is on the productivity of workers and their ability to access key applications.  With a focus on downtime due to refreshes, updates, patches or being remote from the users’ desktop, Citrix is a software/application virtualization solution with a potential for hardware virtualization implementation.

Virtualization Recommendation

With virtualization, the opportunity to take advantage of unutilized or misappropriated resources is a tremendous improvement function within the organization.  As an enterprise wide solution, VMWare would be the choice.  This is based upon the level of development and maturity of the product as well as the long standing reputation within the virtualization segment.  The ability to implement, sustain and benefit from the VMWare opportunity is greater than that of Microsoft and Citrix.  While all three have their benefits, the ability to implement multiple solutions from VMWare has the potential of a higher return-on-investment than the other companies.

References

AMD-V. (2008). Nested Paging. Advanced Micro Devices White Paper.  Retrieved from:http://developer.amd.com/wordpress/media/2012/10/NPT-WP-1%201-final-TM.pdf

Gorman, M. (2004). Understanding the linux virtual memory manager. Upper Saddle River: Pearson Prentice Hall

Saxena, M., & Swift, M. (2010). Flash vm: virtual memory management on flash. University of Wisconsin-Madison. Retrieved from: http://pages.cs.wisc.edu/~msaxena/papers/FlashVM-atc-10.pdf

VMWare. (2014). VMware vsphere 4. Key features. Retrieved from: https://www.vmware.com/files/pdf/key_features_vsphere.pdf