Many believe virtualization is about consolidation; it’s really about emulation and abstraction, which enables agility, flexibility, masking of underlying complexity, and consolidation. We’ve been in the virtualization efficiency era, where the focus and value proposition are around saving, reducing, and avoiding. We’re now entering the effectiveness era, where the focus and value proposition expand to enablement and productivity.
While aggregation and pooling are growing in popularity in terms of deployment, most current storage virtualization solutions are forms of abstraction. Abstraction and technology transparency include device emulation, interoperability, coexistence, backward compatibility, transitioning to new technology with transparent data movement and migration, and supporting High Availability (HA), Business Continuity (BC), and Disaster Recovery (DR). Some other types of virtualization include heterogeneous data replication or mirroring (local and remote), snapshots, backup, data archiving, security, compliance, and application-aware storage.
Virtual Tape Libraries (VTLs) provide abstraction of underlying physical disk drives while emulating tape drives, tape handling robotics, and tape cartridges. VTLs provide compatibility with existing backup, archive, or data protection software and procedures to improve performance using disk-based technologies. VTLs are available in standalone and clustered configurations for availability and failover and scaling for performance and capacity. Interfaces include block-based for tape emulation and Network-Attached Storage (NAS) for file system-based backups. VTLs also support compression, de-duplication, encryption, replication, and tiered storage.
Building a business case for VTLs or disk libraries to support technology transition and coexistence with existing software and procedures is straightforward. If the time it takes to migrate data off older storage systems and onto newer technology can be reduced while maintaining data availability and application access, the result is that the storage resource technology can be used for longer periods, decreasing the time the technology isn’t fully utilized.
The primary focus of virtual storage servers or partitions is to isolate, emulate, and abstract the Logical Unit Numbers (LUNs), volumes, or file systems on a shared storage server. Some storage virtualization solutions have focused on emulating or providing competing capabilities with those of mid- to high-end storage systems. The premise has been to use lower-cost, less feature-enabled storage systems aggregated behind the appliance and switch- or hardware-based systems to provide advanced data and storage management capabilities found in traditional, higher-end storage products.
Inter-system data movement could be used for establishing a BC site as part of an initial synchronizing effort and for moving data to cloud and Mobility Services Platform (MSP) services. Data movement can occur at an entire storage system, file system, file, volume, or sub-LUN (aka block-level) basis.
Another type of data migration, tiered storage, involves moving data in a storage system for tuning or load balancing and capacity optimization. The data movement functionality can occur via host-based volume managers and file systems, or vendor or third-party software running on a server or appliance, including via virtualization platforms, and in storage systems.
Systems that do a lot of data movement on an intra-systems basis require extra processing performance and sufficient internal bandwidth. Automated, tiered storage may help reduce storage cost but could hamper Quality of Service (QoS) or scalability.
Storage virtualization can be implemented in several different ways or locations, including in servers, on appliances, in networking devices, and in storage systems. There are varying opinions about whether a solution is virtual or not. One school of thought is that storage virtualization must support different vendors’ products, while another approach looks at the functionality across a single vendor’s product or products. Which is the correct approach will depend on your technology preferences, your assessment of each vendor’s philosophy, or both. The best type of storage virtualization and best place to have the functionality depends on your preferences. The best solution and approach will enable flexibility, agility, and resiliency; it will complement your environment and adapt to your needs. It could combine multiple approaches as long as the solution works for you and not the other way around.