1. Thin Provisioning – A Comparison of Application Virtualization<br />ThinApp and XenApp<br />Traditional storage allocation methods, sometimes referred to as “fat provisioning”, require blocks of storage capacity be purchased up front, with considerations for future needs and growth. This can result in large amounts of storage space being purchased, but not being used. Thin provisioning addresses this issue by relying on on-demand allocation of blocks of data, and the exact required amount of server space at the time it is required. This allows the storage to be divided between multiple users based on the minimum space required by each user at that particular time. In this abstract I will focus on application virtualization software and its contribution to storage reduction. I will be comparing the application virtualization software VMware ThinApp and Citrix XenApp.<br />VMware ThinApp gives you an application virtualization solution that separates the software application from the operating system. ThinApp converts software, creating a portable application package, allowing the software to run, but eliminating the need to install the software on the system. With ThinApp, an entire application and its settings can be packaged into a single executable file and used across many different Windows operating systems without imposing additional cost and complexity to the server or client.<br />The virtual environment presented to the client is a merged view of the underlying physical and virtual resources, thereby allowing the virtualization layer to fool the application into thinking that it is running as if it were fully installed. ThinApp does not have any pre-installed components and does not require the installation of device drivers allowing applications to run from USB keys or network shares without ever requiring Administrator rights. Also it is able to scan a system before and after an applications installation and create a portable executable based upon changes made to the systems files and registry. Unlike self-extracting ZIP files, ThinApp does not extract files to disk or require system registry changes in order to run applications.<br />An organization can benefit from using VMware ThinApp. There is no client software to install. Applications can be virtualized to work on any operating system, eliminating the need for costly upgrades. Applications can be run from a USB key or within a shared network. There are no changes to the windows registry and no device drivers are installed.<br />The key benefits for IT Directors as claimed by VMware are:<br />Accelerate application migration & deployment to Windows 7<br />Eliminate costly recoding and reduce regression testing costs with independent sandboxes<br />Reduce the cost of maintaining secure locked-down desktops<br />Consolidate Terminal Servers and dedicated application servers<br />Enhance work-force mobility by running applications directly on external media, including USB Flash, CDROM, and unattached laptops<br />Eliminate additional infrastructure investments in server hardware or software<br />Deliver virtualized applications using existing management software delivery processes<br />VMware ThinApp is an excellent thin application solution; however the cost starts at more than $6000, so the price may be out of reach for some small and midsized businesses. <br />Citrix XenApp is an on-demand application delivery solution that allows any Windows application to be virtualized, centralized, and managed in a datacenter and instantly delivered as a service to users anywhere on any device. With Citrix XenApp users can connect to corporate applications within that data center. XenApp can either host applications on central servers or allow users to interact with them remotely or stream and deliver them to user devices for local execution.<br />XenApp components, including application hosting servers, if any, reside on a Microsoft Windows computer, which can be either standalone or part of a larger cluster (farm) of Citrix servers. It is important to note that in addition to concurrent user Citrix licensing, there must exist a Terminal Server Client Access License (CAL) and a Windows Server CAL from Microsoft for each client connection. Both products must be adequately licensed for the environment to function correctly.<br />Citrix XenApp takes the complexity out of distributing applications. Any Windows application can be delivered to users anywhere on any device. All applications are managed from one central location. XenApp delivers applications by an automated process, simplifying delivery.<br />Some of the key benefits as described by Citrix are: <br />Centralize Applications:<br />Centrally configure, store, and maintain a single application image in the datacenter, either on multi-user terminal servers or centralized virtual machines, and enable seamless delivery from any operating system.<br />Configure Access:<br />System intelligence and configurable access controls automatically determine the optimal method for delivering each application based on the user scenario, device capabilities, network performance, connection location, and security profile.<br />Enable Self-Service:<br />Users can subscribe to the applications they need from a simple enterprise app storefront and gain instant access from whichever device is most convenient–PC, Mac, netbook, tablet, or smartphone.<br />Deliver Apps On-Demand:<br />XenApp delivers applications via a high speed delivery protocol for use while connected, or streamed via Citrix application virtualization or Microsoft App-V directly to the device for use when offline.<br />Citrix XenApp is a cost-effective application virtualization solution; however XenApp requires separate client software be installed on end user devices, for both offline use and to connect to the network. This can make the installation cumbersome and requires the use of more hard drive space on end user devices.<br />Both application virtualization solutions have some good benefits. Both allow applications to be shared from a central database and across multiple operating systems. Both offer security benefits. Both deliver applications on-demand. However, having to install client software and obtain licensing for both online and offline access to applications adds and overhead to the Citrix XenApp solution, which can make installation and usage more time and resource consuming. <br />I have used the trial version of VMware ThinApp in another class. It was an easy, fast set up, and a user friendly operation. I was impressed that you could run and entire software applications from a jump drive. You wouldn’t have known you were running virtually. There was no trace of the software having run on the machine after you removed the jump drive either. <br />I have to admit that I started this paper with a heavy slant toward VMware ThinApp, and my research into Citrix XenApp did little to change my mind. ThinApp is simply a cleaner running solution. I believe in a business setting the ease of use and low overhead would more than make up for the extra cost. It is the type of solution that will pay for itself over time by reducing the amount of software installation and maintenance required. Using virtualized applications will also reduce the amount of server space required, thereby conserving resources; another cost saver. It can also provide a secure environment by isolating the application from the host machine; this reduces the chance of the software introducing a foreign entity onto the host system. The portability aspect of ThinApp is also another plus in its favor. With the increasing number of teleworkers in businesses today, having a portable software solution can be a benefit to a growing business. <br />Sources:<br />http://searchstorage.techtarget.com/definition/thin-provisioning<br />http://www.webopedia.com/TERM/T/thin_provisioning.html<br />http://www.vmware.com/products/thinapp/overview.html<br />http://www.citrix.com/English/ps2/products/feature.asp?contentID=2300358<br />