Coraid’s New-Age DAS Throws Out SAN Storage

Progressive storage software maker Coraid has launched a solid-state ATA over Ethernet (AoE) storage virtualisation appliance, the Etherdrive SRX The company claims it has taken the entire concept of tiered storage-area networks – with all their controllers, switches, complications and bottlenecks – and has thrown it out the window.

In its place, Coraid has simplified and optimised enterprise data storage in a manner akin to the old direct-attached storage (DAS) scheme. But this is not your father’s DAS, this is DAS for the 21st century.

Easier Than iSCSI Or Fibre

Coraid CEO Kevin Brown (pictured) said the company’s whole mission in life is to solve cost and complexity issues associated with competing SANs. Founded in 1997, the company has grown its installed base to more than 1,300 customers – including many Fortune 100 and large government customers.

AoE presents disk storage to servers across a standard Ethernet network using Layer 2 connectivity. AoE is a much simpler protocol to process than iSCSI or Fibre Channel, which rely on much more complicated protocol stacks and are based upon complex SCSI command sets.

“Our EtherDrive VSX-Series storage virtualisation appliances use commodity hardware and feature logical volume management (LVM), snapshots, cloning, mirroring and remote replication,” Brown told eWEEK. “We’re growing because our platform really does deliver radical improvements in price-performance and simplicity.”

Coraid founder Brantley Coile, who previously invented the Cisco PIX firewall and Cisco LocalDirector products, began to develop the AoE networked storage protocol in 2000 and released it to the open source community in 2003.

AoE is a simple way to move disk storage out of servers and onto an Ethernet storage network. With the protocol, disk read/write requests are placed directly into Ethernet frames/packets. AoE packets do not need TCP/IP, so they are easy to process. AoE has been included in the Linux operating system kernel since 2005.

Typically, eight-port enterprise SANs are comprised of proprietary hardware and software that is difficult to change up without a lot of cost and effort, especially when major upgrades and fixes need to be made.

“You could afford to have somebody come in, get it up and running, and monkey with it once in a while. It’s not particularly dynamic. However, when you need a new one – in comes the forklift,” Brown said. “With our system, you keep the same software all the time and get 10 or 20 times performance improvements – sometimes better than that, depending on the workload – and you just add more disks as you grow. Works with all operating systems and protocols. Can’t get much easier to use than that.”

Access by Any Computer on the Network

EtherDrive storage can be accessed and shared by any server/host computer attached to the storage network, Brown said. Disks inside EtherDrive storage appliances are usually assembled into RAID volumes and presented as block storage LUNs.

Servers discover and mount EtherDrive LUNs by using a low-cost Host Bus Adapter (HBA) and software driver. The HBA driver presents an EtherDrive LUN, to the host OS, as a local SCSI disk drive, Brown said.

The SRX3200 series of EtherDrive storage appliances from Coraid – which include a load of fast NAND flash drives – are offered as high-performance SAN-like devices that really act more like DAS devices. They are designed to work with 3.5-inch or 2.5-inch serial-attached SCSI (SAS), serial ATA (SATA) or solid-state drive (SSD) disks, Brown said. All the SRXs utilise four 10-GigE (Gigabit Ethernet) connections, enabling high-performance access for virtualisation, cloud and primary-storage applications.

Coraid’s SRX software is priced at about $500 per terabyte and scales to multiple petabytes, Brown said.