BY DAVE SIMPSON
Lending credibility to the emerging iSCSI standard and the convergence of network-attached storage (NAS) and storage area network (SAN) technologies, IBM is readying two products that signal new directions for Big Blue's storage division:
- The TotalStorage IP Storage 200i, which is due in late June, is a "pre-iSCSI" disk array that provides block-level I/O over standard IP networks such as Ethernet. The iSCSI announcement came in the midst of related IP storage announcements from vendors such as Cisco, Emulex (see story on p. 12), FalconStor, and Nishan Systems (see InfoStor, March 2001, p. 1).
- The TotalStorage NAS 300G is a "gateway" with an Ethernet front-end and a Fibre Channel back-end connection, linking NAS and SAN configurations and functionality.
In some environments, iSCSI provides an alternative to Fibre Channel which, until recently, has been the only viable interconnect for building SANs. But analysts applaud IBM for acknowledging the current shortcomings of iSCSI and targeting the 200i array at relatively low-end environments.
"We're targeting the 200i at workgroups, small departments, ISPs, and SSPs that find that Fibre Channel SANs are not viable," says Jim Pertzborn, general manager of storage networking at IBM. "But iSCSI today is not an alternative to Fibre Channel for customers that need all the capabilities of Fibre Channel SANs."
iSCSI enables block-level I/O over standard IP networks such as Ethernet.
In a report on the 200i an-nouncement, the Evaluator Group consulting firm concluded: "Given the amount of overhead, the Intel server-based storage system, and the performance issues of using IP, IBM has positioned the 200i correctly in the workgroup and departmental space. The issues of security in IP accesses are not typically a major concern in these markets either. This product should not be a high-performance storage system, but will satisfy some customer environments where a need for networked storage is felt, but the complexity of a Fibre Channel SAN or the expense of a NAS product might be beyond the ability of the customer to bear."
According to analysts, a number of developments are required before iSCSI can compete head-on with Fibre Channel in the data center space. First, vendors have to address IP-related reliability and security issues. Second, realizing the full performance potential of iSCSI will require host bus adapters or network interface cards that offload TCP/IP processing from the host CPU to onboard hardware accelerators. These souped-up cards are expected before year-end.
Finally, widespread adoption of iSCSI is not expected until the standard is finalized. Participants in the Internet Engineering Task Force (IETF) standardization process say the iSCSI specification is likely to be completed by the end of this year.
Analysts say IBM's 200i appliance is the first array-with the exception of 3ware's disk arrays-to be compliant with an early version of the iSCSI specification.
How it works
"Rather than being handled through the SCSI port on the client or server, storage requests are routed to the TCP/IP stack, encapsulated as SCSI-over-IP [via software], and sent out over the IP network," explains Pertzborn. "The storage request is then de-encapsulated on the 200i." Linux-based software handles the iSCSI requests, encapsulation, and de-encapsulation. Standard Ethernet network cards can be used in the servers and clients.
The 200i is available in single- or dual-CPU versions, with capacities ranging from 108GB to 1.7TB. Features include Linux-based microcode; support for 10/100Mbps Ethernet or Gigabit Ethernet; and support for Windows NT/2000 and Linux clients. The iSCSI configuration requires "iClient" initiator code on all participating nodes, which is available over the Internet.
A network-attached storage (NAS) gateway has an Ethernet front-end and a Fibre Channel back-end, uniting NAS and a storage area network.
The 108GB and 216GB configurations are priced at approximately $20,000 and $40,000, respectively.
NAS+SAN * IBM also recently introduced the TotalStorage NAS 300G gateway, which is "a bridge from the IP NAS network into a Fibre Channel SAN," according to Pertz-born. It includes dual Pentium III processors on each node and supports standard NAS file protocols such as CIFS, NFS, HTTP, FTP, and NetWare. The diskless NAS appliances have a Gigabit Ethernet front-end and are available in a single-node version ($44,000) or a dual-node configuration ($95,000) with fail-over capability. IBM/ Tivoli's SANergy file-sharing software is pre-packaged and provides direct block I/O access to data over the SAN from clients.
The 300G is the first NAS device from IBM's Storage Systems Group. (IBM's Netfinity server division has been selling a NAS server since late last year, and the 300G is based on a Netfinity server.) The device is expected to compete primarily with EMC's Celerra, which provides a NAS front-end to EMC's Symmetrix arrays.