Storage area networks take the place of hot spares

The storage area network, or SAN, is so new that agency network managers have had
little time yet to evaluate the high-availability storage architecture.


SANs are designed to save money for sites that buy twice as many servers as they need
for data processing just to protect their databases against hardware failure.


“It’s now possible to build much larger clusters because we can have more
systems touch more disks,” said Roger Klorese, senior product manager for Veritas
Software Corp. of Mountain View, Calif.


Microsoft Corp. recently staked a SAN claim by announcing a joint initiative with
Compaq Computer Corp. to extend its Windows Socket application programming interface to
SAN interconnect technology. 


Storage experts predict that SANs will simplify campuswide data replication.


High availability in the past has meant having to nearly double server costs. “If
you wanted to protect databases, you would buy a second machine and set it up as a hot
standby,” Klorese said. A centralized SAN storage architecture means less overbuying,
he said.


Full-frame video and multimedia training applications are most likely to benefit
immediately from the high data bandwidth SANs provide, Klorese said. 


SANs can carry both high-level IP traffic and the big “but not very bright”
block protocols conveyed between hosts and disks or tapes, Klorese said. SANs have
100-megabyte/sec Fibre Channel components because Ethernet cannot guarantee the delivery
of blocks in order. Block protocols “aren’t that friendly yet toward Gigabit
Ethernet,” he said. 


SANs evolved from channel-attached interconnect components such as IBM Corp.’s
Enterprise Systems Connection and High Performance Parallel Interface hardware. Both are
fairly expensive single-platform architectures for data mirroring. 


Fibre Channel vendors put the 100-megabyte/sec serial connectivity interface into
servers, disk drives, RAID storage modules, switches, hubs, adapter hardware, test
equipment, cables, connectors and software.


The enterprise storage vendors promoting SANs include Storage Technology Corp. of
Louisville, Colo., EMC Corp. of Hopkinton, Mass., MTI Technology Corp. of Anaheim, Calif.,
Data General Corp., Artecon Inc. of Carlsbad, Calif., Amdahl Corp. and Silicon Graphics
Inc.


Veritas makes high-availability Veritas Cluster Server storage management software for
mixed Unix, Novell NetWare and Microsoft Windows NT storage area networks.  

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