A number of tape library vendors recently outlined their plans for supporting iSCSI, and each is going about it a different way.
For example, Advanced Digital Information Corp. (ADIC) has manufactured an iSCSI development board based in part on Adaptec's iSCSI Storage Protocol Accelerator (SPA) ASICs and network processors. Commercial shipments are expected in the second half of this year, according to Paul Rutherford, vice president of technical software development at ADIC.
The company chose Adaptec's ASICs because ADIC had settled on ASICs from Platys, which Adaptec subsequently acquired. Also, "they were concentrating on target chips, whereas a lot of the other ASIC vendors were focusing on HBA [host bus adapter] initiator chips," says Rutherford.
In April, Quantum/ATL plans to deliver an iSCSI card for its P-Series tape libraries that will be based on a PowerPC RISC processor and a software implementation of iSCSI. A version for ATL's M-Series libraries is scheduled for the third quarter. Both of these initial implementations will be based on the same engine (PowerPC) that drives ATL's NDMP libraries. A faster iSCSI implementation based on a custom ASIC is expected late this year, according to Gene Nagle, product line manager at ATL.
Nagle says that the PowerPC/software implementation of iSCSI is able to run the tape drives at full speed in a configuration with one engine per drive.
Spectra Logic is currently supporting iSCSI in a software-only implementation in its Tape Appliance Operating System (TAOS). Bill Reed, vice president of marketing and business development at Spectra Logic, says the company will implement hardware-based support for iSCSI when the standard is finalized-which is expected in the second quarter.
Crossroads, the market-share leader in SCSI-to-Fibre Channel routers, is also working on iSCSI technology that it hopes to OEM to some of its tape library partners. Library manufacturers will be able to embed Crossroads' routers in their libraries, making them appear as native iSCSI devices.
Tape library vendors generally agree about when end-user adoption of iSCSI SANs will pick up. "You'll have basic functionality in the middle of the year or the third quarter," predicts ATL's Nagle, "although you may still be missing the ability to do things like discovery and special management functions."
"We think the window of opportunity for iSCSI SANs will be the fourth quarter," says ADIC's Rutherford. "It's a big assumption that we'll have native iSCSI target devices such as disk arrays before the end of the year. We'll need lower-cost target chips."