What are the differences between VM-aware storage and virtual storage appliances?
When I talk about VM-aware storage, I'm talking about when the storage operations are tightly integrated with the virtual machine, and indeed may be attached to the VM. For example, that would associate storage management operations -- or capabilities such as replication, snapshots [and] backup -- with the VM, and they therefore move with the VM. This is sometimes done through application programming interfaces, where you have a typical third-party array that has the VM APIs built into them or it might even be software-defined storage that is deployed within a VM.
In contrast, virtual storage appliances (VSAs) are when you have heterogeneous storage on the back end fronted by a common storage controller and storage management on the front end. So it really behaves like a single, traditional storage pool of LUNs and volumes even though the back-end storage might be heterogeneous in nature. Some examples here would be things such as Cisco Unified Computing System, EMC VMAX, HDS, IBM SAN Volume Controller and NetApp V-Series, and most vendors have some flavor of it today. So those terms are kind of apples and oranges because they do different things.
The bottom line for IT managers is to explicitly understand what the vendor's definition of VM-aware or VSA is -- and it's not safe to assume that the definition that one person is using is applied by the other. So if you do that, you can make sure no confusion exists when the solution is applied.
About the author:
Phil Goodwin is a storage consultant, freelance writer and frequent TechTarget contributor.
This was first published in February 2014