NETWORK WORLD FUSION FOCUS: AMY LARSEN DeCARLO
on STORAGE IN THE ENTERPRISE
Today's Focus: The lure of the SAN
03/14/00

Dear Wincenty Kaminski,

Today's Focus: The lure of the SAN
---------------------------------------------------------------
By Amy Larsen DeCarlo

E-business is changing how businesses value information. Information
has become a strategic asset that gives companies an edge over their
market rivals. Companies use intelligence to identify new markets and
make contact with prospective customers. In this media-saturated era,
information itself is packaged and sold as a product. This makes the
ability to supply users with fast access to stored information on a
continuous basis absolutely crucial.

Companies are clearly coming to a crossroads in their storage
implementations.  With estimates for Internet storage capacity needs
doubling every three months, IT professionals are hungry for a scalable
solution to help them consolidate control of stored information. They
often look to storage-area networks (SAN) as a better option to manage
their information storage systems than distributed models.

Today, most organizations rely on a distributed storage model that uses
file servers to process I/O requests from end users and other
application servers. In this model, all requests for data go through
the file server that owns the attached storage disks, and only one file
server can tap data on a particular disk via a SCSI bus.

This model has several shortcomings.  First, the amount of data a
server can access is restricted to the number of disks supported by the
bus, which limits the capacity of a single file server.  Second, because
the server processes each I/O request, it risks becoming a bottleneck.
Third, this server model carries some daunting availability limitations,
because only one file server is allowed to access a set of disks.  If
that file server or any of its SCSI connections fails, then users and
other application servers lose access to the stored files.

This model carries other major disadvantages.  Distributed file servers
rely on the data transport network to run backup and recovery operations
which can eat up bandwidth and slow normal network transmissions to a
crawl.  Finally, this decentralized setup is difficult to manage from
both a logical and a physical perspective.  File server based storage
systems are distributed throughout the enterprise, so it is often
difficult to assess current and future capacity needs.  And because
these servers use a parallel cabling scheme to link the file server to
the disk array, they can also be cumbersome to set up and manage.

SANs promise to mitigate the problems that plague conventional file
servers, largely through consolidation of control.  These specialized
storage networks claim higher availability, faster performance,
centralized management, and by their architecture, the capability to
remove bandwidth-intensive data backup and recovery operations from the
LAN. This frees up the LAN for normal data communications and ensures
smoother back-up operations.

Using high-speed transports like Fibre Channel, SANs offer a high-
performance network optimized for moving storage data. SANs also make
way for new storage implementations like LAN-free backup. And, because
Fibre Channel can support distances of up to 10 kilometers, SAN devices
can be widely distributed, but also centrally managed as one network.

Yet, as was the case with LANs in their younger years, SANs are still
developing. Vendors are still working out major product interoperability
issues, while companies deploying SAN technology struggle with how to
merge the very different worlds of storage and networks and manage both
together. Ultimately the hope is that, like LANs, SANs will develop into
a mature and highly manageable solution that supplies substantial
benefits at lower costs.

Given that storage deployment and ongoing support costs can total 10
times the acquisition price for the equipment, the consolidated
management capabilities of a SAN may deliver the biggest benefit to
business.

To contact Amy Larsen DeCarlo:
------------------------------
Amy Larsen DeCarlo is an analyst with Enterprise Management Associates
in Boulder, Colo., (http://www.enterprisemanagement.com), a leading
analyst and market research firm focusing exclusively on all aspects of
enterprise management. She focuses on storage management, application
management, and security. In her position, she oversees market research
and contributes to custom project work in her focal coverage areas.
Prior to joining EMA, Amy spent five years covering enterprise
management for industry trade magazines, including InformationWeek and
Data Communications. She can be reached at
mailto:decarlo@enterprisemanagement.com

~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
FOR RELATED LINKS -- Click here for Network World's home page:
http://www.nwfusion.com
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

Storage Networking Industry Association (SNIA):
http://www.snia.org

Fibre Channel Industry Association (FCIA):
http://www.fibrechannel.com

SCSI Trade Association (STA)
http://www.scsita.org


Other storage-related articles from Network World:

Legato primes storage resource mgmt, Network World, 03/13/00
http://www.nwfusion.com/archive/2000/89776_03-13-2000.html

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