NetApp is the latest entry into the field, with its Data ONTAP Edge product, which was announced in late June and will ship in August. ONTAP Edge runs in VMware ESX virtual machines (where the product is actually designated ONTAP-v, which leads us to suspect other versions are in the offing), and requires that the host have a hardware RAID controller. The software is limited to managing 5 Tbytes, which should be plenty for most small offices, and provides most of the features of NetApp's hardware-based systems running ONTAP 8.1.1.
NetApp says pricing hasn't been set yet, but it ironically claims the product to be the "best price/performance to meet growing needs." The company's lowest-priced hardware product lists for about $8,000, so we can assume the virtual version will run a good bit less than that. Like most other virtual products, the appeal is that it can be managed right along with the company's physical NetApp appliances and requires no additional hardware at the remote site.
NetApp's virtual appliance is somewhat unique with its special requirements for server hardware--namely, that it sports a RAID controller. Most other virtual appliances have no such requirement--indeed, the bigger use for virtual appliances may be in public cloud environments, where nothing is really known about the underlying hardware.
The Virtual Cloud
Cisco's router in a virtual machine, for example, has little application in remote offices as it would likely be enough running on card in a physical Cisco ISR router. Instead, the cloud services router is intended to be used in the public cloud to terminate a VPN connection and provide other services within the cloud that would normally run on Cisco hardware. It will be a vital part of Cisco's (not-so) Open Network Environment SDK. Other products with unique cloud applications include F5's Big-IP Local Traffic Manager VE. The virtual appliance can be used in the cloud to do load balancing and provide other optimization that physical Big-IP LTM appliances do.
Riverbed was an early entrant to the virtual appliance game, with Virtual Steelhead appliance,s dating back to 2010. But the company hasn't stopped there--it's also virtualized the SAN, with its Granite systems. That product family, announced earlier this year, is known as edge-VSI (virtual server infrastructure). Edge-VSI provides block-level service, whereas the Steelhead appliance provides file-level service.
And there's more virtualization going on at the company: At Interop this year, Riverbed showed its Steelhead Cloud Accelerator. Steelhead cloud was developed with Akamai to provide caching services for certain SaaS applications. So far, the product works with Google Apps, Salesforce.com and Microsoft Office 365.
Whether you're looking to take advantage of IaaS offerings or just looking to get more functionality in remote offices without adding more hardware, virtual appliances are worth a look.