One of the first options when choosing the best software-defined storage architecture for your organization encompasses products that are aligned with, integrated with and usually part of the hypervisor stack. VMware now produces Virtual SAN, which is a layer of software the firm is calling software-defined storage, that is part of its software stack. Hyper-V has what it calls Clustered Storage Spaces, and it's written by Microsoft and integrated directly into its Hyper-V stack.
A second software-defined storage architecture option includes third-party, hypervisor-agnostic products that can be used with VMware, Hyper-V, KVM or Citrix. These are software products -- Maxta, Starwind Software and StoreMagic, for example -- that perform the same functions as, and in many cases better than, the leading software-defined storage vendors. They provide the same functionality, but they're not dedicated to a particular hypervisor. The storage repository they create might also be able to be shared among different hypervisors.
The third option, virtual storage, has been around even longer. This option includes products such as IBM Spectrum Virtualize (formerly SAN Volume Controller) or DataCore SANsymphony that virtualize all the capacity of a SAN's hardware and surface the specialty software into a software layer so it can be allocated more efficiently. When you have an application workload that needs storage with specific data protection schemes, you can just select the settings you need from the management interface and it's allocated with the storage.
Storage virtualization is probably the best software-defined storage architecture implementation approach because it fits with most legacy infrastructure. You don't need to use a direct-attached storage configuration like you do with the others -- you just build a common pool of storage and allocate it at will.
These software-defined storage types are different modalities, and they cater to different needs. A storage administrator with an all-VMware shop, and who wants a single vendor to control everything, might be inclined to go with the VMware-specific Virtual SAN. An administrator who wants to support a diversity of hypervisors with a common infrastructure might choose the third party hypervisor-agnostic or virtual storage option.
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