Through virtualized storage, multiple storage devices are pooled together to behave as a single device. This facilitates tasks such as storage management and data backup. However, the transition away from a non-virtualized environment can be a complex one.
This tutorial addresses frequently asked questions about the use of virtualized storage technology for medical images. As new regulations force health care providers to generate electronic records that must be stored for many years, virtualized storage is an increasingly viable option.
- What is virtualized storage, and how does it work?
- What is a virtual SAN, and how can it be used for medical images?
- What are the benefits of using virtualized storage?
- What are the challenges of using virtualized storage?
- What are the key considerations when buying software?
- What are the key considerations when buying hardware?
The concept of virtualized storage has been around for some time, but it can be confusing, as different vendors have presented and implemented it in different ways. To provide a common frame of reference, the Storage Networking Industry Association defines storage virtualization as abstracting the internal functions of a storage system from the host computers, applications or network resources so that storage can be managed independently.
Virtualization technology in general implies that a computing function is isolated from its physical components. In this case, virtualized storage technology is applied to aggregate devices or functions to conceal their complexity. Typically it describes a system of multiple physical disk drives feeding into what appears to be one unit, which can be managed centrally.
Virtualized storage implementation can be done in a variety of ways, depending primarily on where the virtualization software is deployed. The software can be installed on a regular server, which is known as host-based storage virtualization. It can also be deployed as a package deal on a dedicated device, or installed on a switch.
A virtual SAN is a component, or subnetwork, in a storage area network where traffic can be segregated. Virtual SANs offer the potential for improved security over physical SANs because they operate independently, making the overall storage system less vulnerable.
When dealing with sensitive -- and highly regulated -- material such as medical images, the security of the storage system is vitally important. Virtual SANs are particularly useful for medical images because many providers want to keep their image data separate from other applications.
Virtual SANs also allow for convenient tiered storage. When images need to be available instantaneously for clinical review after they have been captured, they can be held in a primary -- or tier 1 -- storage location. After review, they can be moved into tier 2 storage, and, ultimately, they can be moved into tier 3.
The popularity and capabilities of digital medical imaging have grown dramatically in recent years, resulting in an enormous amount of data stored in a wide variety of storage systems. Storage requirements are only expected to rise, making stored data increasingly difficult to manage.
Health care organizations often have invested in storage technology from multiple vendors over the years, further complicating the management challenges. Virtualized storage reduces the complexity inherent in managing a large number of storage devices, since all the storage resources are treated as a single entity.
Configuring multiple virtual storage devices is faster and easier than multiple physical devices because it is performed from a single interface. Data can be moved among drives in different locations without shutting down any systems. Pooling all of the storage resources also makes it easier to back up and recover data -- a vital function in the highly regulated health care industry.
Deploying virtual storage, like deploying virtualized environments in general, can represent a significant transition for an IT organization, and it isn't necessarily easy. Health care organizations have not tended to be early adopters of IT, and there is limited expertise available to address the challenges involved with storage virtualization, experts caution.
Making sure that all storage resources are interoperable when deploying virtualization is key. Devices, software and peripherals all need to work together, and periodic changes and upgrades are a given when it comes to storage systems. IT professionals have to be sure that management tools work in the virtualized environment as well.
Virtualization can add stress to the system, putting greater demands on the physical hardware and affecting its performance. When migrating to virtualized storage, hardware reliability is more important than ever, but ensuring sufficient performance and reliability for the virtual environment can be costly. Virtualized storage can also create a drain on bandwidth.
When evaluating virtualized storage products, first consider how to implement the system. For a relatively inexpensive and easy way to implement virtual storage, software can be deployed on a host device, which typically is a regular server, rather than a dedicated device or a switch. However, to scale up this type of virtualization, additional servers are required, since these devices can handle only so much data, and this adds to the maintenance challenges and costs.
However IT professionals choose to purchase and deploy storage virtualization, they will want to consider software licensing costs and maintenance overhead. Every new server deployed may involve a new license, and licenses typically have to be renewed every year, so consider both upfront and recurring costs. Software upgrades are inevitable, so evaluate the time and energy they will demand of the IT staff.
Consider what impact the software will have on the performance of hardware, as well. Make sure servers are up to the virtualized storage software’s requirements; these include memory, CPU, and I/O resources. Look at the reporting, monitoring and management features. Finally, evaluate the product’s characteristics with regard to how data is moved among different storage tiers.
If an organization is purchasing a virtual SAN, the considerations are more complicated. Virtual SANs typically are partitioned within a large SAN. This allows for segregated traffic, which makes it easier to troubleshoot or configure. Virtualization can also be applied to merge separate SANs into one virtual entity.
Virtual SAN software generally is deployed on a SAN switch. Be sure that virtual SAN products can support whatever fabrics are running in the data center. Determine the maximum throughput between virtual SANs as well, because it can be tricky to add bandwidth or update hardware if using vendors that approach storage virtualization differently. Finally, look at routing behaviors, security features and the impact that the virtual SAN products will have on management tools and processes.
Virtualized storage hardware plays a key role in the system, so it is important to know its capabilities and its limits. The first thing to consider is where the virtual storage software is going to be deployed -- hosted on an ordinary server, coming with a dedicated server or installed on a switch -- because each approach has its own advantages and disadvantages.
For managers who want a single storage platform, then a hardware-based virtual storage package could make sense. However, if the organization is likely to work with three or more storage vendors, or is operating a very large data center, then it might make more sense to deploy virtual storage at the switch level.
To deploy virtual storage on an ordinary server or switch, be sure that the software and hardware are compatible. Determine how the hardware connects to the network and make sure it supports network protocols. To implement a virtual SAN, be sure that switches and other hardware are interoperable.
IT managers must be sure to understand the downtime and interruptions involved in the physical installation and setup. Have a fallback plan at the ready. Consider any disruptions to users and applications caused by upgrades or changes. Test the latency the platform experiences when directories are being accessed, as well as any other performance issues. Finally, don’t forget to evaluate the security features.
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This was first published in June 2011