If you put much stock into what VMware and Microsoft are saying, then you would believe everything in the data center will soon be controlled by software or virtualized. They may be right, since the advantages of virtualized storage can bring new levels of flexibility to the data center. In this article, I’ll explain the advantages of, and expose the challenges to, virtualizing storage.
One of the most interesting use cases for virtualizing storage is for disaster recovery. Imagine if you could leverage storage virtualization to bring up a warm data center by replicating storage between remote locations using storage products from two different vendors. Virtualizing storage solves the technical challenge of desperate storage solutions, allows you to use a storage array built from generic x86 hardware at the warm data center and brings advanced capabilities – such as snapshots – to older platforms.
Virtualizing storage for production
To virtualize production storage, a product must first attach natively to the production storage area network (SAN) as a client node. This means that whatever connectivity approach you use in the production system must also exist on the hardware used to virtualize the storage array.
The next requirement is the ability to “see” the volumes to be replicated. This is probably the most complicated part of using storage virtualization for replication. When you are replicating between two arrays from the same vendor, you can use their products to do block-level replication. However, this isn’t an option when using a storage virtualization product as a proxy.
One option is to use the storage virtualization product as a production controller. You can provision all available physical storage to the virtualization platform and then provision the production storage from the virtual storage platform. This works when you want to create a single virtual SAN from a pool of disks on different arrays. But, in our case, we are looking to take an existing production setup and replicate it without impacting production.
While not positioning itself as a virtual SAN provider, Actifio offers many of the features associated with virtual SAN technology. The company focuses on the concept of reducing the physical footprint of data by providing virtualized copy of data for disaster recovery, test and development.