Software-defined storage and storage virtualization are often confused. While they are similar, it is worth pointing out some key distinctions.
Software-defined storage shifts the hardware layer that provides deduplication, snapshots and replication into the software layer. This enables a software-defined storage layer to be placed over existing storage resources that do not have these advanced features. As a result, you give older storage new functionality without having to replace an entire storage frame. This also moves these features into the hypervisor layer, where they can be integrated at a much deeper level. The hypervisor then has much more control and can help drive more application-centric policies regarding storage performance, capacity and redundancy.
Storage virtualization combines multiple pools of storage into one or more logical containers. This can be done to increase capacity, enhance performance or enable storage tiers. Storage virtualization also simplifies and consolidates multiple storage resources into virtual volumes. These pools of storage can then be managed by storage-driven policies, enabling more control at the VM level. Storage-based policies also allow for better performance tracking, which can be used to automate key service levels and compliance.
While software-defined storage and storage virtualization have different functions, they work in concert. When a vendor is discussing software-defined storage, it already has a storage virtualization layer included as part of the product.
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