Just what are storage hypervisors? There are several companies that claim to have storage hypervisors. Wikipedia states that a hypervisor is “conceptually one level higher than a supervisory program”. We also know that from our normal use of hypervisors that they manage the underlying resources that a guest uses. Do these definitions work for a storage hypervisor?In short, these definitions work for storage hypervisors as well.
Storage Hypervisors deliver resources to other systems as required and provide a higher level of control above and beyond our normal storage devices. In fact, storage hypervisors are well known as being able to manage multiple types of underlying hardware regardless of vendor. So in a way Storage Hypervisors act as the single control point seen by those making storage requests. This simplifies command and control of disparate storage devices. There is no need for those making storage requests to care whether the underlying storage is presented as FCoE, iSCSI, NFS, CIFS, or FC to the storage hypervisor, as the storage hypervisor presents in its own form.
Many of the modern storage hypervisors sit either as a physical device or a virtual device between the work loads they are serving to and the storage underneath them that generally come from disparate hardware and capabilities. Many storage hardware vendors may also have their own storage hypervisors but are geared to work with mostly their own hardware, think IBM San Volume Controller, which is interesting way of adding high order storage functionality to underlying IBM storage components. Or they could ship as software that either installs on a physical machine or as a virtual storage appliance. In addition, storage hypervisors can do many different things:
- Augment existing storage with higher order functions such as VAAI, VASA, Deduplication, Replication, Mirroring, etc. Datacore SanSymphony v9 falls into this category by providing VAAI support as well as increased replication and redundancy in an N+1 configuration, which is improved from just two nodes with previous versions.
- Optimize existing storage for specific workloads by providing a workload optimized file system. Virsto falls into this category for virtual desktop workloads.
- Gateways to other services such as cloud storage. Twin Strata falls into this category with the ability to provide a single interface for accessing various forms of cloud storage.
- Aggregate existing forms of storage into just one storage entity such as local, and remote storage functionality. VMware’s Storage Virtual Appliance and Microsoft’s Hyper-V storage functionality both provide this type of storage hypervisor.
Is there one storage hypervisor that fits the entire set of functionality? Perhaps, but the real reason to use one is to aggregate existing forms while either augmenting or optimizing storage workloads. Datacore provides much of this functionality as does Falconstor and several others. The key element is whether they are general optimizers (by adding a huge amount of memory which is used as read and write cache to the storage hypervisor system) or specific optimizers such as ones that create specific use case filesystems.
No matter how you look at your virtual and cloud tenancy you most likely are looking to optimize your storage in some form regardless of what is under the covers. Perhaps it is time to review the current batch of storage hypervisors to determine if they fit your needs? But first decide do you need to augment, optimize, aggregate, or provide a gateway service to your existing storage network? Or are you looking to provide even more security as we discussed previously?