Storage Virtualization
What is storage virtualization, and how is it used?
In the enterprise storage world, storage virtualization is a technique for pooling physical storage devices such that IT is able to address a single “virtual” storage device. Though now largely eclipsed by the cloud model, storage virtualization offered significant operational and cost efficiencies over “bare metal” storage (in which physical storage devices are addressed directly). With virtualized storage, organizations reduced compatibility concerns and boosted the performance and security of storage environments.
When using virtualized storage, admins had to consider a variety of issues:
- Compatibility and interoperability: Storage virtualization environments must be compatible with underlying hardware infrastructure, networking components, servers, operating systems, management tools, and hypervisors. It i’s essential to have compatibility with protocols such as NFS and Fibre Channel to ensure seamless integration and APIs to allow integration with automation tools to provide orchestration and integration.
- Performance and latency: Critical applications have performance requirements that must be met by the virtualized storage environment. Admins must evaluate storage controller capabilities, network bandwidth, disk I/O capacity, and caching mechanisms to understand how they impact performance and latency.
- Data security and integrity: A virtualized storage environment should supports data encryption to ensure data safety during transit or at rest and provide access and authentication controls at granular levels to block unauthorized access. Robust backup and disaster recovery solutions are required to ensure strong data protection for virtualized storage.
How does storage virtualization fit within the cloud storage model?
Storage virtualization as a technique has been around for decades, and it set the stage for cloud-based storage (in which massive quantities of individual storage devices are virtualized into enormous pools of virtual storage). In recent years, storage virtualization has largely given way to the cloud storage model, as enterprise IT has seen the benefits of leaving the previously mentioned challenges of deploying and managing virtualized storage to the cloud vendor.
In the cloud computing model, VM and application admins define the storage they need with a few parameters — storage type (i.e., block, file, object), capacity, performance, bandwidth — and the cloud vendor immediately makes the desired storage available from its own virtualized storage pools. In the background, the cloud architecture handles all of the provisioning, configuration, and protection tasks that were once handled in the data center by a storage admin.
The operational advantages of the cloud model are obvious: enterprise IT no longer needs to be concerned with managing ever-more complex virtualized storage environments, and lines of business enjoy dramatically shorter provisioning times. Cloud storage enables on-demand access to storage resources and dramatically simplifies data management workflows. That powers faster time to value — and accelerates digital transformation.
From a financial perspective, the cloud model gives enterprises far more choice and flexibility in consuming storage resources. Typically, cloud vendors offer opex, pay-as-you-go billing for cloud storage consumption, but recently the most advanced cloud offerings also include a capex option that enables enterprises to combine the data sovereignty and security advantages of on-prem storage with a cloud operational experience.
How does storage virtualization work?
In storage virtualization, physical storage hardware is mirrored in a virtual volume. To construct a simple virtual storage environment, multiple physical disks are combined into a grouping that uses a single server. Virtual storage or logical storage blocks are assigned to the same server and help to redirect the input/output (I/O) traffic.
The physical disks are separated from the virtual volume by a virtualization layer that enables operating systems and applications to access and use the storage. Virtual storage software takes the I/O requests and sends them across the overall pool of storage to the appropriate storage devices.
The physical disks themselves are divided into small blocks of data, or objects known as logical unit numbers (LUN’s), logical volume (LV), or RAID groups. These blocks are presented to remote servers as a virtual disk. They look just like a physical disk to the server, rather than the collection of storage devices that make up the overall pool of storage in the virtualized environment.
In a more complicated environment, RAID arrays can function as virtual storage. Here, multiple physical drives mimic a single storage device that stripes and replicates data to multiple disks in the background. This process improves I/O performance and protects the data from a failure in any single drive.
The way data is accessed from the physical drives requires an additional step for the virtualization software. Along with creating a barrier between the physical and virtual storage devices, the virtualization software creates a map using metadata that allows the stored data to be located quickly. In some cases, the software creates an algorithm to find the data even more quickly.
Creating virtual storage can be achieved on both block-level and file-level storage environments. Virtualizing a storage area network (SAN) involves adding a translation layer between the hosts and the storage arrays. In this type of storage virtualization, servers are redirected to virtualized LUNs instead of LUNs on the individual storage array. These virtualized LUNs remain on the virtualized device. Virtualizing a NAS involves removing the dependencies between the data accessed at the file level and the location where the files are physically stored.
What are the different types of storage virtualization?
There are a few ways that storage can be applied to a virtual environment: host-based, array-based, and network-based.
Host-based
Most often used in HCI systems and cloud storage, host-based virtualization relies on software to direct traffic. In this method, physical storage can be attributed to nearly any device or array. The host, or a hyper-converged system comprised of several hosts, presents virtual drives to guest machines of any configuration, such as virtual machines (VMs) in an enterprise, PCs accessing file shares, or servers accessing data via the cloud.
Array-based
In array-based storage virtualization, servers are physically located, and which array is being accessed is not visible to the servers or users accessing the storage. Here, a storage array serves as a primary storage controller, using virtualization software to pool storage resources from other arrays. The array also can present different types of physical storage as tiers, rather than a disparate collection of devices. Such tiers can be made up of solid-state drives (SSDs) or hard disk drives (HDDs) on the various arrays.
Network-based
The most common form of storage virtualization is network-based. Here, all storage devices are connected in an FC or ISCSI SAN by a network device. These interconnected devices present themselves as a single virtual pool within their storage network.
What is the difference between server and storage virtualization?
Organizations have a few virtualization technologies to choose from, and business needs will drive which one is best. Most companies have virtual desktops in their workplace environment, as remote work appears to be here to stay. And part of that remote work environment includes application virtualizations, since desktops can use fewer resources to do the work needed without applications’ operating systems physically residing on the desktop itself.
However, there’s more to the virtualization story. When a server is virtualized, enterprises can see high availability and more efficient disaster recovery. That’s because the operating system is separated from the hardware and the machines accessing it can be treated as a file. As a file, these servers can be stored on the SAN, which allows a large degree of mobility for data access. If one server fails, since all virtual servers are stored on the SAN, another server can be called upon to host the activity instead.
Server virtualization also enables the hardware to be adjusted on demand, creating a more elastic system. As workloads shrink, servers can be discontinued and conversely, as workloads increase, the same servers can be turned back on. Thus, with fewer servers on at all times, an organization can save money on electricity, cooling, and redundant hardware that sits unused much of the time.
Storage virtualization also helps increase availability, especially when used in tandem with server virtualization. When storage is virtualized, it isn’t paired to any particular server. Thus, the storage can be managed from multiple sources and used as a single repository. In addition, many servers can access the data stored on the SAN, making SAN utilization much simpler.
What are the benefits of storage virtualization?
- Lower cost: Because virtual storage doesn’t require the typical hardware redundancies needed in traditional enterprise storage architectures for disaster recovery, fewer appliances and/or software licenses need to be purchased. This saves enterprises from the significant cost of up-front financial commitments.
- Saved time: Virtualized storage not only reduces downtime—planned and unplanned—but it also makes upgrading much less time-consuming and disruptive.
- Scalability: With virtual storage, organizations no longer need to forecast their long-term future storage needs or pay for all that capacity upfront. Instead, IT can take advantage of dynamic provisioning that responds to changing needs on demand.
- Easier management: Virtual storage simplifies and improves resource use, providing an easy addition/deletion of storage without interrupting applications. It also enables seamless data migration and streamlines advanced feature application across the storage pool.
- Reduced risk: If a disk drive, storage controller, or power supply were to fail, each is already mirrored in the virtual array, so the risk of disruption is considerably reduced. That virtual redundancy limits slower performance and increases storage efficiency and flexibility.
- Increased productivity: Virtual storage not only delivers 100% availability, but it also has the potential to accelerate app and service deployments to realize value faster.
- Improved efficiency: Getting faster storage with better capacity utilization is the biggest benefit. It also provides more stability to data access and processing. In addition, virtual storage ensures 100% utilization and little chance of running out of capacity.
HPE GreenLake delivers the best of the cloud storage model
With advanced storage services on the HPE GreenLake edge-to-cloud platform, HPE has led recent innovation in the cloud storage model. Customers have on-demand, enterprise-grade storage available at their fingertips, fully protected by Saas-based backup and disaster recovery services. These solutions simplify data management with an intuitive cloud experience and extend customer flexibility by enabling cloud-model storage either on-prem or in the cloud:
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- HPE GreenLake for Disaster Recovery — Slash the risk of data loss with simple, self-service disaster recovery that deploys in minutes and delivers industry-leading RPOs and RTOs. Think of it as disaster recovery at your fingertips.