Access to network storage, the myriad of network connections and paths used to get to the data, grows in a non-linear manner with high demand and full utilization of the network. Hence, network storage is really a networking challenge, not a storage challenge. Fibre Channel and iSCSI were designed by storage experts. ATA-over-Ethernet (AoE) was designed by network protocol experts.
In the early days of Ethernet, network speeds were sufficient for basic communication between computers, but certainly not for network storage. The original Ethernet standard(10Mbit/s) evolved into Fast Ethernet(100Mbit/s) and next into Gigabit Ethernet(1Gbit/s), with an even more recent 10 Gigabit Ethernet(10Gbit/s). Once Gigabit Ethernet arrived in the market it had widespread adoption, therefore produced in mass quantities making the NIC's very affordable for everyone as commodity products. Finally Ethernet had the speed at 1Gbit/s that could theoretically match the media transfer rate of hard drives at 1Gbit/s or higher. The challenge now became how to fully realize the performance speeds of Ethernet and to make the market aware of how today's Ethernet can readily handle the demanding networking load required by network storage.
The inventor of the Cisco PIX firewall and CORAID co-founder wrestled with the challenge to fully realize the performance capabilities of Ethernet for network storage by designing an open network protocol called ATA-over-Ethernet (AoE). The significance of AoE is its very lightweight footprint, with a specification of only 11 pages. AoE is the enabling framework that allows EtherDrive SAN to be high performance and affordable. Because AoE only relies on Ethernet, all of the components to create and manage an Ethernet based network are available as very affordable, commodity networking hardware. Taking this approach has allowed CORAID to create high performance storage appliances by assembling commodity technologies, thus keeping cost per GB of storage at $0.50, a very small fraction of the cost of other storage hardware in the market. VMware ESX users now have the much needed and unheard of combination of "High Performance and Affordability" for their network storage.
The robust and flexible nature of AoE has allowed CORAID to develop EtherDrive SAN storage with an almost unlimited amount of expansion. Each CORAID EtherDrive storage appliance is deemed a "shelf". AoE allows addressing, or access, to 65k of these AoE shelves. Each shelf in turn can host 255 targets. Each target supports 48-bit logical block addressing, or 144 Petabytes. Currently, available drive capacity and hardware limitations only allow for 10's of Terabytes per shelf. With over 16.7 Million (65k Shelves * 255 targets per shelf) targets available on a single network, each with a theoretical capacity of up to 144 Petabytes, it becomes clear why CORAID's almost unlimited expansion capabilities become critical to storage growth.
Just as important, if not more important than storage growth and capacity, is access to network storage. Without scalable network access, network storage quickly becomes a bottleneck for the entire system. For VMware ESX, CORAID helps solve this dilemma by simply adding one or more 2-gigabit (dual 1-Gig) EtherDrive HBA to get more bandwidth and leverage available network capacity. Fibre Channel and iSCSI cannot scale in this manner and are therefore doomed to become network storage bottlenecks because they are not robust enough to scale to existing network capacity cost effectively. By today’s standards, the ultimate performance is achieved by using one or more 20-gigabit (dual 10-Gig) EtherDrive HBA. This enables VMware ESX to fully leverage high performance network storage at maximum network capacity with the benefit of the most affordable price.
For information on CORAID EtherDrive SAN visit www.coraid.com