By Dave Simpson
Next month, LeftHand Networks will begin shipping a RAID device that combines block-level (SAN) and file-level (NAS) I/O over Ethernet. The primary benefit to end users is that they don't have to buy separate devices for the two types of data access, which could in turn reduce storage management costs. NAS-SAN devices combine the performance advantages of storage area networks with the ease-of-use benefits of network-attached storage.
With LeftHand's Network Storage Module (NSM 100), administrators set the RAID module, or drives within the module, for either file-level or block-level I/O. The NSM can handle both types of traffic simultaneously. However, the device does [ital]not[ital] support simultaneous access to the same drive, a feature that will come in a later version.
The company refers to the NAS-SAN convergence category as Network Unified Storage (NUS). Dozens of vendors are working toward combining NAS and SAN I/O in a single device. According to Dan Tanner, a senior analyst with the Aberdeen Group consulting firm, in Boston, a partial listing of those vendors would include BlueArc, EMC, FalconStor, IBM, KOM, Pirus Networks, Sistina Software, Storage Computer, Times N Systems and TrueSAN Networks. (For more information, see InfoStor, August Special Report, "Combining the benefits of NAS and SAN," p. 19.)
The NSM 100 attaches to standard Ethernet or Gigabit Ethernet networks. Block-level I/O is handled by LeftHand's Advanced Ethernet Block Storage (AEBS) protocol, which provides functionality that is similar to the emerging iSCSI standard. However, LeftHand officials claim performance advantages over iSCSI.
"There's a lot of unnecessary overhead in the iSCSI approach," contends Dave DuPont, vice president of marketing and business development at LeftHand, in Boulder, CO. "We believe that AEBS will provide significantly higher performance."
However, DuPont points out that LeftHand will be able to wrap iSCSI around the AEBS protocol to achieve compatibility. Final ratification of the iSCSI standard by the Internet Engineering Task Force (IETF) is expected in the second quarter of 2002.
The 1U NSM modules can be clustered in pairs, and can be managed as a single logical device via the company's Storage Control Console. Each module includes four IDE (Ultra ATA) disk drives, an 866MHz Pentium III processor, redundant power supplies and up to 1GB of cache. RAID 0 and 10 configurations are supported, as well as Windows NT/2000, Solaris and Linux. On the NAS front, the NSM supports CIFS, NFS, HTTP and FTP. LeftHand is initially focusing on Microsoft Exchange and Oracle database environments.
Including all software, a 160GB configuration is priced at $14,995; 320GB, $24,995; 480GB, $34,995.