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In an effort to prove the
viability of storage area networks (SANs) based on the
emerging iSCSI standard, three vendors this week demonstrated
a configuration running at "wire speed" over Gigabit
Ethernet. Participating in the demo were Alacritech, Hitachi
Data Systems, and Nishan Systems.
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iSCSI is an IP storage standard
under development in the Internet Engineering Task Force (IETF)
that can complement and/or provide an alternative to Fibre
Channel SANs. The standard is expected to be finalized around
midyear.
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In the demo, a server with
Alacritech's "1000x1 Server and Storage Accelerator"
card was attached to a Nishan 4300 storage switch, which, in
turn, was connected to a Fibre Channel-based Hitachi Freedom
disk array. Alacritech's I/O card offloads TCP/IP and iSCSI
protocol processing from the host CPU. (For more information
on iSCSI and Alacritech's TCP/IP offload engine [TOE] card,
see ATA
puts the squeeze on SCSI and iSCSI
SANs inch closer to reality.)
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The server-to-switch connection
was clocked at 219MBps--the "wire speed" of Gigabit
Ethernet. However, participants acknowledged that the test was
based on Intel's Iometer benchmark code, which does not
reflect real-world application performance. Nevertheless,
officials from Alacritech and Nishan claim that iSCSI
performance will be comparable to that of Fibre Channel. It
should also be noted that the 219MBps speed was achieved in
full-duplex (bidirectional) mode.
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"iSCSI allows end users to
mix and match IP and Fibre Channel architectures, or to use an
all-IP storage configuration," says Barry Hauser, vice
president of marketing at Alacritech. Another advantage of
iSCSI, according to proponents, is that it lets IT shops
leverage existing infrastructure (TCP/IP networks) and
expertise.
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In addition to purportedly
providing a lower-cost alternative to Fibre Channel, iSCSI is
also expected to benefit applications such as storage
consolidation, business continuance, remote backup and
restore, and remote data access.
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But the key to the
demonstration was performance. "Wire-speed performance
makes iSCSI suitable for a wide range of storage
applications," says Tom Clark, director of technical
marketing at Nishan. However, iSCSI performance in real-world
application environments has yet to be proven.
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In addition to achieving
wire-speed performance (with benchmark code), the tests
demonstrated a relatively low CPU utilization--slightly less
than 8%--due to the TCP/IP offload capability of the
Alacritech card. The card, which Alacritech refers to as an
integrated storage network interface card (IS-NIC), is priced
at $999 and can be used in network-attached storage (NAS) and
SAN configurations.
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