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A number of tape library
vendors recently outlined their plans for supporting iSCSI,
and each is going about it a different way.
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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.
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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.
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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.
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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.
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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.
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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.
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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."
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"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."
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InfoStor January, 2002
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