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IT professionals sometimes tussle with how to use storage technology in healthcare to improve application performance.
At the core of the issue, hospitals that decide to implement desktop virtualization often place a great deal of emphasis on ensuring that virtual desktops are able to perform at least as well as their physical counterparts.
Even so, good virtual desktop performance does not always translate into good application performance. The reason for this dilemma? Unlike physical desktops, apps might not always be installed directly on the virtual desktop, and therefore may not benefit from the virtual desktop's underlying storage hardware's capabilities.
Different locations for virtual services
Administrators in virtual desktop infrastructure (VDI) environments often decouple the applications from the virtual desktops through app virtualization. Doing so makes it easier to maintain the virtual desktop images.
This approach also means that the virtualized app probably resides in a different physical location from the virtual desktops. Virtual desktops are almost always hosted on dedicated hardware, such as hyper-converged systems. Virtualized applications, on the other hand, can reside almost anywhere -- including in the cloud.
In spite of the fact that virtualized applications are not installed directly on virtual desktops, there are some things that VDI admins can do to help ensure that end users have a good experience.
First and foremost, it is important to make sure that virtual desktops are provisioned with adequate hardware resources. This includes CPU, memory, network bandwidth and storage input/output operations per second (IOPS). IOPS is a common performance measurement for storage devices.
Cost reduction creates performance concerns
VDI admins often face pressure to reduce costs by achieving the highest possible virtual desktop density per host server.
However, excessively high density almost always translates into degraded performance. This is an important consideration, because even though a virtualized application might not be installed directly onto a virtual desktop, the application has at least some level of dependency on the virtual desktop -- the level of this dependency varies depending on the virtualization technology that is being used.
If the virtual desktop performs poorly, then the end user will not have a good experience.
Administrators must also consider the individual applications that the users will run. Some applications are simply more demanding than others.
Storage tiers hold an advantage
From the perspective of storage technology in healthcare, it usually makes sense to define various storage tiers rather than placing all of the organization's virtualized apps onto a single storage device.
Applications with light I/O requirements can be placed on commodity storage, while applications with heavy I/O demands might do better on an all-flash array.
This dual approach saves money, because the organization is not trying to place all virtualized applications onto a single high-performance storage device. The approach also improves performance across the board, because IOPS are being distributed across multiple storage devices, rather than a single array having to handle the collective IOPS from all of the virtualized applications.
Another thing that administrators can do to ensure better overall application performance is to ensure that the connectivity between the virtual desktop hosts and the virtual application storage is adequate for the anticipated workload. Having high performance storage means very little if the storage link cannot keep up with the storage array's capabilities or with the storage I/O demand.
Watch for load storms
Depending on how the organization's infrastructure has been constructed, bandwidth may need to be evaluated at multiple levels.
For example, high speed connectivity would likely be required between the server hosting the virtualized applications and a storage array, but connectivity between the virtual application host server and the virtual desktop host must also be considered if a performance bottleneck is to be avoided.
A final issue to consider is that of application load storms. Load storms occur when multiple users launch a virtualized application simultaneously, such as at the beginning of a nurse shift.
Load storms are usually brief, but tend to result in performance degradation until they are over. As such, storage technology in healthcare must be able to deliver a sufficient level of IOPS to overcome these demand spikes if performance degradations are to be avoided.
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