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Reduce the currency of e-business to its essence, and
you are left with the elemental medium of exchange --
information. How it circulates! The amount of
information shared each year, according to Berkley,
is now at the exabyte level, an exabyte being 108
terabytes. This is a staggering quantity, accounting
for all data, audio, and video shared on a global
basis. What is truly staggering, however, is that 93
percent of this information is stored digitally.
As vast as this hoard of information may seem, it
is only getting larger, and the amount of stored
information is bound to grow at an ever-increasing
rate, as enterprises augment traditional business
models with e-business models, mediating online
transactions, interactions, and collaborations --
business to business, consumer to business, and person
to person.
The growth in stored information poses several
challenges. How do we manage the sheer volume of
market, customer, and product information and
multimedia content? How do we make all of this
information instantly accessible to applications and
users, wherever they may be? How do we satisfy the
7-by-24-by-365 availability demands that attend
globalization and e-business? How do we meet the need
for distributed back-up systems dictated by sound
business practices and government regulations (such as
in the financial services industry)?
Taken together, these challenges suggest we'll soon
face a painful crunch: on the one hand, we'll need
more elaborate provisions for storage (redundant
systems to ensure critical information continues to be
available under failure conditions); on the other
hand, we'll have less time to administer over these
provisions (drastic reductions in the time available
for backups, updates, and maintenance).
Shifting Investments
In 1999, the storage capacities shipped by the top
five storage vendors exceeded 10,000 terabytes. Not
only does this represent a significant capital outlay,
but also attendant management costs have been
estimated by Yankee Group to be $12/MB/year.
Approximately 80 percent of this storage today is what
is called direct attached storage (DAS), dedicated to
a particular server or mainframe over interfaces such
as SCSI and ESCON. While directly attached, these can
be local or remote, for example to an off-site backup
data site. The remainder is connected to storage
networks, dominantly to Storage Area Networks (SANs).
A SAN is a high-speed network dedicated to
information management. More formally, a SAN is a
combination of technologies -- including hardware,
software, and networking components -- that provides
any-to-any interconnection of server and storage
elements. The overall trend is towards accelerating
the use of SANs and towards networked attached storage
(NAS). Today, NAS represents less than 1 percent of
the storage market, but it promises to extend the
benefits of the IP/Internet networking paradigm to
storage applications.
At this point, we might ask why the idea of
extending this paradigm to storage should be so
attractive. To answer this question, let's take a
quick look at the evolution of computing and how it
has influenced storage considerations. In the early
days, a single computer vendor provided a proprietary
solution to a single buyer: the data processing
manager. With the minicomputer, the process changed,
and departments bought their own computing solution.
The market transitioned to multiple solutions sold to
multiple buyers, resulting in incompatible,
proprietary data processing systems. Over time, users
realized they needed to combine all data processing
into an integrated environment. This requirement
opened the door for open standards-based solutions.
Now, companies are connecting their mainframes with
enterprise and department servers for distributed
client/server architectures. Distributed computing
along with parallel processing has resulted in a
significant increase in process-to-process
communications. At the same time, the data storage
requirements have exploded. This new paradigm only
works if data can be moved and shared quickly. The
need for very high-bandwidth and extremely low-latency
I/O is paramount.
Distributed computing, client/server applications,
and open systems give today's enterprises the power to
fully integrate hardware and software from different
vendors to create systems tailored to their specific
needs. These systems can be fast, efficient, and
capable of providing a competitive edge.
Unfortunately, many enterprises have taken a far less
proactive approach with their storage systems.
Strategic Storage?
Storage, unlike a Web application server or a database
system, is rarely viewed as a strategic tool for the
enterprise. This view, however, is beginning to
change. With the explosive growth of e-business, IT
managers are working intensely to keep pace with
managing the significant growth of data. They are
installing high-performance storage systems to meet
the demands for smaller backup windows and greater
application availability. However, these systems are
often complex and expensive to manage. In addition,
DAS by its nature creates a performance bottleneck in
providing access to data to a broad range of users and
applications.
For example, an e-commerce transaction may require
information from multiple databases, directly attached
to application servers. As the volume of Web hits
increases, the network can become choked, slowing
response times to unacceptable levels -- not just for
the e-commerce applications, but for every application
that must send information across that same network.
In addition, there are the complications of
managing information in a heterogeneous environment.
Limited integration between products from different
vendors requires separate management tools, and the
variety of operating systems and user interfaces adds
to the burdens shouldered by administrative staff.
Basically, in a heterogeneous environment, the
complications include investments in redundant skills
and management software, which often lead to
labor-intensive processes, as staff are obliged to
perform the same functions multiple times across
multiple servers. The results: a limited ability to
rapidly adjust to new business initiatives, and a
higher total cost of computing.
To improve data access and reduce costs, IT
managers are now turning to storage networking, and
specifically SANs, to provide the foundation for the
development of the corporate information utility. The
move to SANs is motivated by the need to manage the
dramatically increasing volume of business data, and
to minimize its dampening of network performance. Key
factors include:
- E-business -- Securely transforming internal
business processes and improving business
relationships to expedite the buying and selling
of goods, services, and information via the
Internet.
- Globalization -- The extension of IT systems
across international boundaries.
- Movement to real-time -- The need to exchange
information immediately for competitive advantage.
- Business agility -- The ability to continually
adapt, while immediately accessing and processing
information to drive successful business
decisions.
Storage Area Networks
A SAN is a dedicated, centrally managed, secure
information infrastructure, which enables any-to-any
interconnection of servers and storage systems. SANs
facilitate universal access and sharing of resources,
providing the flexibility to satisfy the new business
requirements.
SANs are flexible because they eliminate the
one-to-one relationship between individual servers and
critical business data. In addition, they separate
information management from information processing.
SANs can be configured to provide servers in different
locations with direct access to huge amounts of shared
storage resources. SANs also enable direct
storage-to-storage connectivity -- for example,
between multiple disk arrays or between a disk array
and a tape library -- allowing management activities
such as backups and archiving to take place
independent of any server.
SANs provide a faster, more effective way to deal
with rapidly increasing volumes of information. With a
separate information management network, additional
capacity can be "plugged in" as needed with minimal
impact on the performance of application or
transaction servers, LANs, or WANs.
Performance is further enhanced by improved backup
and recovery capabilities. With a SAN, backup and
recovery can take place without involving either the
existing LAN or WAN, or individual application or
transaction servers. With information no longer tied
to any one server in particular, failure of a single
server is less likely to degrade information
availability. In addition, SANs support advanced
multi-server clustering solutions for new levels of
information availability and business continuity.
Management also is greatly simplified. A SAN
permits the use of a common set of tools and a single
point of control to manage a centralized pool of
information. Finally, SANs also permit near-real-time
updates of remote disaster recovery sites for higher
levels of disaster tolerance.
SANs On A Fiber Diet
SANs are most typically based on a "fabric" of Fiber
Channel hubs, switches, and gateways connecting
storage devices -- such as disk arrays (RAID), CD-ROM
libraries, optical disk or tape libraries, or JBOD
(Just a Bunch of Disks) -- servers and workstations on
a many-to-many basis. Application and transaction
servers are attached to both the SAN and to LANs or
WANs, creating what appears to be a massive pool of
data.
Fiber Channel is a family of ANSI standards, which
defines a common, efficient transport system
supporting multiple protocols, including IP, SCSI,
HIPPI-FP, and video. It can also support raw data
transport using native Fiber Channel guaranteed
delivery services.
Fiber Channel, as a channel/network standard,
contains network features that provide the required
connectivity, protocol multiplexing, and reach. It
also supports traditional channel features for
simplicity, repeatable performance, and guaranteed
delivery. Profiles define interoperable standards for
using Fiber Channel for different protocols or
applications. It runs at speeds from 33 Mbps to 2 Gbps,
and 10 Gbps in the future, supporting multiple
cost/performance levels, from small systems to
supercomputers.
The transmission is isolated from the control
protocol, so point-to-point links, arbitrated loops,
and switched topologies are used to meet the specific
needs of an application. A high-end SAN can scale to a
total system bandwidth on the order of terabits per
second. Fiber Channel delivers a high level of
reliability and throughput with efficient bandwidth
utilization over metro dimensions. Fiber Channel has
also been applied in applications as diverse as
high-performance CAD/CAE networking, movie animation
and post-production, and imaging.
Beyond SANs
There is clear advantage in moving storage systems
beyond the local area. This can be done over multiple
lower speed point-to-point circuits through expensive
conversion/gateway devices or ‘natively' over
multiple dark fiber. However, two other significant
storage networking trends are emerging, one based on
NAS, the other on optical MAN's.
Network Attached Storage
NAS provides a common pool of storage that can be
shared by multiple servers and clients, regardless of
their file system or operating system. NAStorage is
designed to separate storage resources from network
and application servers, to simplify storage
management and improve the reliability, performance,
and efficiency of the network, thus increasing the
overall productivity of the organization.
NAS appliances have a streamlined architecture
designed for one function: to serve data files to
clients in heterogeneous network environments. Powered
by an operating system optimized for file I/O
activity, file-serving performance is greater than
that of a general-purpose server, which is designed to
perform a multitude of functions. A file system is
located and managed on the NAS device, and data is
transferred to clients over industry-standard network
protocols (for example, TCP/IP over an Optical
Ethernet) using industry standard file sharing
protocols (SMB/CIFS, NCP, NFS, AFP, or HTTP). This
intelligence on the NAS device enables true data
sharing among heterogeneous network clients.
The NAS approach offers several advantages.
Separating storage from the server reduces the file
serving activity, relieves I/O bottlenecks, and
increases server bandwidth. CPU cycles can then be
dedicated to handling application requests, resulting
in improved client response time.
Because the NAS approach separates storage
resources from the server, NAS decreases both the
number of components and the amount of file I/O
activity. These decreases reduce the probability of
server downtime, and increase the reliability of the
network and application servers. Because NAS servers
operate independently of network servers and
communicate directly with the client, files remain
available in the event of network server downtime.
By enhancing reliability, the NAS approach helps
minimize costs attributable not only to storage
problems, but also to server failures. Storage-related
problems, according to Dataquest, account for over 60
percent of server failures. And network downtime
resulting from server failure costs organizations
thousands of dollars per hour.
Optical MANs
Based on Dense Wave Division Multiplexing (DWDM),
optical MANs can substantially simplify metropolitan
networking environments for DAS extensions and SANs,
as well as for NAS, providing unprecedented levels of
scalability. And scalability may be improved both in
terms of bandwidth and also application technology,
with delivery being accomplished with carrier-grade
reliability.
Optical MANs can support channel extension and
storage networks running within the Enterprise System
CONnection Architecture (ESCON at 200 Mbps) or via
FIber CONnection (FICON at 1 Gbps) -- for "big iron"
DAS environments; Fiber Channel SANs; inter-router
links between campus LANs running long-reach Ethernet;
Point-to-Point Protocol (PPP) over 45-Mbps links or
Asynchronous Transfer Mode (ATM); and high-quality
video links for employee communications and training.
Optical MANs can accept any of the above optical
signals in native mode (from 16 Mbps to 2.5 Gbps),
without hardware changes, and then map them onto
wavelengths. Consider the example of a change from a
DAS to SAN or NAS architecture (or, equivalently, from
a multiprotocol to a universal IP on optical Ethernet
environment). Since such a change can be accomplished
without hardware changes, the investment in
high-performance, ultra-high-reliability optical MAN
infrastructures may be preserved.
The wide deployment of DWDM systems is also
enabling the option of subscribing to a storage
networking service, variations of which are being
planned by some service providers. These services
could provide remote mirroring, disaster recovery,
centralized disk-on-demand, business continuity, and
centralized tape backup. Such services could offer the
benefits of extended reach, consolidation of fibers,
reduction of equipment, carrier-grade reliability, a
forecast tolerant architecture easily adapted to
unforeseen changes in traffic, and centralized
monitoring and control.
Summary
With storage predicted to account for over 75 percent
of all computer hardware expenditures over the next
five years, it's increasingly important for today's
enterprise to have an effective strategy for storage
networking to make data available whenever and
wherever it's required. As networks have become
faster, the bottleneck has shifted from the network to
the server and its DAS. Server, storage, and
networking vendors have implemented significantly
different product designs to take advantage of
parallel processing technology for DAS, NAS, and SAN
products. Optical DWDM systems, with its convergence
path to optical Ethernet, have emerged as a common
high-performance foundation with the ability to
support all three architectural approaches.
Tony Rybczynski is director of strategic marketing and technologies
for Nortel Networks' Enterprise Solutions unit. For more information,
visit the company's Web site at www.nortelnetworks.com.
E-mail questions or comments to tonyryb@nortelnetworks.com.
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