|Businesses today are relying
more and more on information systems for successful operation in the
corporate world. Both employees and customers build these information
systems around network data that is created on a daily basis. Data
created in the course of running your business exists throughout the
network and is one of your company's most valuable corporate assets.
As you begin to look at data as a corporate asset, a strategy must
be developed that will guarantee the security and availability of
your data, while still allowing it to grow.
According to META Group:
- Most organizations are facing exponential data
- Business are demanding 24x7 access to their
- IT managers need to adopt a storage strategy
for managing, protecting and growing their network storage assets
How do you grow your available network storage
and keep it under control? For most IT staffs, this is a difficult
task because your network evolved as the company grew. You added
workstations when needed, and you added storage to your existing
server as needed. Eventually you ended up with a hodge-podge of
technology as your network. In many networking environments adding
more storage means hanging another server off of your network or
taking down an existing server and installing additional hard drives.
This type of storage increase just adds to the complexity of your
existing storage environment. As your storage requirements grow
to support data collection from broadband Internet access, creation
of large graphic files, archival of e-commerce transactions and
the exponential growth of email databases, you must develop a consistent,
concise strategy for corporate network storage.
Developing a storage strategy for your network
environment begins with answering three basic questions:
- How do you want to connect additional storage
to your network?
- How will you manage all of the storage devices
and the data on your network?
- How will you ensure the security and availability
of the data on your network?
A good strategy for network storage addresses
each of these questions and allows for the expansion of your network
storage pool without affecting either the availability or security
of the existing data on the network.
Storage Architecture -- Connecting Storage
to Your Network
When you see the message "Out of disk space
on Drive X," the network demand for storage is exceeding your
plan or ability to add capacity. This is a sure sign that you need
to develop and implement a more practical strategy for network storage.
For the first part of your strategy, you must decide which storage
architecture best suits your environment. There are 3 basic storage
architectures available. Direct Attach Storage (DAS), Storage Area
Network (SAN) and Network Attach Storage (NAS). The following definitions
for each type of storage architecture can help you decide which
one will work best for your application.
Direct Attach Storage (DAs)
Direct attach storage is the old way of doing
things. DAs is storage connected directly to a file server via SCSI.
With a direct attach storage system storage is local to a specific
file server. This single server controls all information. DAs can
also be referred to as captive storage or server attached storage.
Adding storage to your network using this model requires installing
another network server with additional storage capacity. Another
method might also entail bringing down an existing network server
and installing additional storage devices into it, or connecting
new storage devices to it via external cabling. Again, this is the
old way of doing things and the demands on today's networks do not
allow for the downtime required for this type of implementation.
Performance: Direct Attach Storage is the slowest
of all of the storage architectures. Attaching directly to storage
servers means that processors in the server need to manage application
requests and move data across the bus and monitor traffic on the
network simultaneously. This creates too many demands on the network
to provide quick access to attached storage.
Scalability: Storage volume is tied to server
capacity in DAs model. Adding storage requires server downtime,
physical space in the server and in some cases new servers. Scalability
is severely limited.
Availability: Storage in the DAs model is also
tied to server availability. If an individual server goes down,
all of the attached storage becomes unavailable, leaving you without
access to your data. The complexity of network server hardware and
operating systems adds unnecessary failure points in your storage
Cost of ownership: Adding the cost of general
purpose network servers to the cost of storage makes DAs one of
the most expensive ways to add storage to your network.
Storage Area Network (SAN)
SANs are high-speed networks that enable the interconnection
of heterogeneous systems and storage elements. SAN gateways deliver
transparent performance that attaches devices across multiple interfaces
while permitting each to deliver its full performance capability
across the SAN network. By putting storage devices on a separate
high-speed network via a SAN, data can be directly accessed by multiple
servers, workstations and PCs and be managed as a centralized storage
pool. Sans need the bandwidth of interconnects such as Fibre Channel
for optimum performance, availability and scalability. But because
TCP/IP does not run over Fibre Channel yet, some interim SAN implementations
may use legacy networks such as Ethernet or FDDI. When IP on Fibre
Channel becomes available, all control and data traffic for server
backup will be offloaded from the LAN to the SAN. SAN implementation
is very complex because of all of the interoperability issues that
can arise. Some vendors are trying to make it easier by supplying
a "SAN-in-a-box." Unlike NAS, installing a SAN is not
a do-it-yourself project.
One of the greatest challenges for Sans is interoperability.
The goal is for UNIX, Windows NT and Netware servers to have access
to the same storage and share the same data. Today users cannot
freely mix and match devices from different vendors because there
are different device-level formats for each operating system. Once
operating systems adopt a common structure at the device level sharing
devices will become easier. Despite its current drawbacks, Sans
promise relief for enterprise storage-level issues.
Performance: Sans improve performance by relieving
congested LANs of high volume data traffic generated by backups,
large data migrations, business intelligence systems and digital
video and audio applications. Storage response time is faster because
Fibre Channel links can transfer data at 100MBps. The potential
problems with interoperability Sans can be difficult to manage because
all of its components are designed for maximum throughput.
Scalability: Multi-channel SCSI controllers can
only support a maximum of 30 devices, while a Fibre Channel fabric
of interconnected switches can address thousands of ports. Bandwidth
can be allocated on demand and network reconfigurations are relatively
simple. Sans allow users to increase storage capacity or re-map
department needs without bringing down the system and disrupting
data access, as all the disks are centrally managed from one location
Availability: Sans allow distributed servers to
access large, consolidated storage resources for data-intensive
applications. Shared storage pools can be accessed by multiple systems.
In SAN architecture, all servers can have direct access to all storage
devices, allowing one server to provide fail-over protection for
dozens of other servers.
Cost of Ownership: By creating a central storage
pool for the entire user community, Sans can lower total cost of
ownership. Fewer administrators are required to manage the storage,
management is centralized from a single management interface and
storage can be purchased separate from servers. The cost of storage
can be amortized over more servers and the storage can be dynamically
allocated and reallocated for maximum capacity usage. Also, Fibre
Channel's high-speed and low latency shortens backup and restore
times, freeing LANs and WANs for business applications that improve
productivity and enhance revenue.
Currently, Sans are more expensive to implement
than NAS because of the investment required in Fibre Channel hubs,
switches and Fibre Channel-to-SCSI bridges. However, the price gap
between Fibre Channel and SCSI is narrowing and the larger the enterprise,
the higher the return on the investment. Given the right set of
management tools, enterprises can see a return on investment in
approximately two to three years.
Network Attach Storage (NAS)
The concept of Network Attach Storage is quite
simple. NAS attaches special-purpose storage appliances to the LAN,
which can be shared by application servers, workstations and PCs
on the network. These appliances have only one job -- file serving.
NAS devices can be distributed across a large network and managed
centrally to provide a common pool of storage that can be shared
by multiple servers and clients, regardless of their file or operating
system. This enables efficient allocation of storage, alleviating
the problem of one server running out of storage while another may
have more than needed.
Unlike Storage Area Networks (Sans) implementation is simple and
straightforward with Plug and Play compatibility. NAS appliances
use standard file-system protocols, such as Network File System
(NFS) and Common Internet File System (CIFS) for data sharing across
multiple operating systems.
NAS is slower than SAN, but faster than DAs NAS offers users dedicated
file server appliances that provide fast access and high-availability
storage to UNIX and Windows NT clients on a network. Data access
time is fast because the system only serves files. Files are offloaded
from the host to free CPU cycles for other cycles. Separating the
storage from the server also increases network reliability.
NAS allows you to separate your storage capacity from your server
capacity and with NAS companies add storage as needed. NAS products
scale to multiple terabytes, and by offloading file serving to these
devices, servers can support more users. But be sure to consider
your future storage needs. As your requirements increase, large
numbers of NAS devices can be difficult to manage. While small NAS
devices are great for projects or workgroups, larger systems may
be necessary for mainstream data storage.
The simplicity of NAS makes it more reliable than traditional LAN
file servers and eliminates many failures induced by complex hardware
and operating systems. Because the NAS device communicates directly
with the client, files remain available, in the event of network
server downtime, thus increasing data availability.
Cost of ownership:
Specialized for high-speed file serving, NAS devices are significantly
less expensive than general-purpose network file servers. Servers
across different operating systems can share access to NAS devices
so that enterprises can save money on hardware, maintenance and
administration by consolidating data on fewer devices in a central
Managing Data and Storage Devices
Even though businesses are increasingly dependent
upon information systems to sustain day-to-day operations, storage
management has only recently become a hot topic for IT departments.
Most companies have all their data reside on RAID with little thought
on how to address future data growth. The common practice, up until
now, of simply adding more RAID to the network and backing it up
is detrimental to business operations because of the time and cost
associated with it.
Another routine the IT departments used to consolidate
network data had users manually remove all older files that were
dormant or aged past a certain number of days. This practice worked
in part because users weren't dealing with the exponential data
growth. Today's electronic marketplace emphasizes accessibility
of both current and past email, financial and healthcare records.
So in environments where protocol to remove data from the network
are not only inefficient, records for e-commerce transactions and
accounting information, by law, cannot be altered or moved. So what
is the solution? Many network administrators are still improperly
addressing the issue by adding more hard drive space to the network
via DAs or additional RAID subsystems without understanding the
long-term ramifications. Adding storage to a network by increasing
the RAID pool affects access speed and adds to backup window length
and space requirements.
As you begin to develop a storage strategy for
your network, many issues and potential problems should come to
mind. How can your network operate with the increased downtime associated
with backup? Where are you going to find the budget for an additional
RAID system that may only last you another 6-8 months before maxing
out? How are you going to finance and manage the increased IT staff
needed to control your growing storage pool? The solution to your
problems involves moving your network data to a cost-effective storage
system while still providing users with a quick and seamless method
to retrieve their data.
To manage data effectively you must understand
how your users create information on the network. One of the best
ways to do this is to look at your data allocation by age. Categorize
your data into 0-30, 31-60 and 60-plus day old windows. Every allocation
will be a little different based upon your business activities and
data types. On average, most of the data on your network will fall
into the "over 30" day category. Typical environments
have somewhere between 20% and 30% of their data created in the
last 30 days. After you complete this analysis, you should have
enough information about your storage environment to forecast what
potential problems are in your future.
A complete storage system could include any or all of the following
types of storage devices:
Online storage devices
Online storage offers the highest performance available on the market
today. As a result, hard disk systems have the highest price-point
for entry or space. Active data best resides on an online storage
device because of RAID's high write transfer and load speeds. Demand
for primary storage is being driven by the digital convergence of
automating commonplace business functions and the role of the Internet.
More video, audio and image data makes its way through computer
networks, driving the demand for 24/7 availability for mission-critical
Industry studies have shown that only 30% of all
data residing on a typical network is regularly accessed, leaving
a major portion of expensive RAID systems to ineffectively store
unused data. As a result, the practice of migrating data from online
to NearLine storage devices has begun to grow in popularity. In
applications where high volumes of data reside, a combination of
online and NearLine storage devices co-existing on the same network
behave as two components of a complete storage solution.
NearLine storage devices
NearLine storage devices are becoming increasingly popular in the
storage market for offering multi-terabyte capacity and high performance
at mid-range cost.
Data housed in NearLine storage is typically not
needed on a regular basis, but when called upon, needs to be accessed
quickly and automatically.
Although NearLine storage systems access data
in terms of seconds, rather than the millisecond speeds that RAID
offers, NearLine is not intended as an alternative to magnetic disk,
but rather as a more efficient solution for growing storage requirements.
Although NearLine storage systems need software applications to
operate, the need for second tier storage is increasing because
current practices do not adequately protect critical data on any
level. Tape backup requires excessive server downtime and provides
minimal support for seamless, on-demand access to data resources.
Available backup windows are shrinking as the average storage capacity
grows and the organizational demand for 24/7 availability increases.
By employing NearLine storage, administrators can migrate data back
and forth between online and NearLine status automatically to effectively
delay the next RAID purchase, lower the backup window and add the
functionality of long-term archive.
NearLine storage maintains data permanently and
securely, while still making it easy to retrieve, manage and control.
Built around the most robust storage technology on the market today,
NearLine Storage Devices provide random access capabilities, portability
and a fifty-plus year shelf life, all at a fraction of the total
cost of RAID.
Backup storage devices
In terms of pure functionally, and cost of ownership,
tape is the best choice for network backup. With data transfer speeds
of 15MB/second; no other removable technology streams data as fast.
Magnetic tape's popularity in the arena of backup
storage is primarily due to its cost-per megabyte. Combined with
high portability and improving random access capabilities, magnetic
tape will continue to play a very important part in the complete
storage strategy via backup and disaster recovery.
For large archival projects that don't need to
re-visit old data, the price point and functionality of tape is
unbeatable. Tape exists, and will continue to be used for network
backup and disaster recovery. However in environments where archived
data is retrieved and used on a regular basis, tape should not be
regarded as the best choice for stable, long-term storage.
Long Term Archive devices
The final piece of the complete storage solution
is long-term archive. Again, magnetic tape has traditionally been
the favored as the medium of choice in this arena, however the storage
industry is increasingly aware of the benefits of NearLine storage.
While primarily operating as a means to store
dormant or less-requested data, the design characteristics of NearLine
Storage Systems (NLSS) also lend themselves to operate as long-term
archive devices. NearLine storage systems record data via laser,
avoiding any physical contact with the media, eliminating any wear
and tear issues. NearLine media is also not as sensitive to surrounding
elements as tape, boasting fifty-plus year shelf life while offering
unprecedented random access capabilities beyond the competition.
With the ability to store multiple terabytes of
data, the need to store information offline is eliminated. The days
of physically searching for tape cartridges stored in vaults and
loading them into a drive have instead been replaced by a simple
file search and execute command via computer to automatically retrieve
and deliver the data quickly and seamlessly.
In order to formulate a comprehensive storage
strategy, understanding your current and future storage needs will
help you get a better idea of what a complete solution should
look like and cost.
Up until now, system administrators and IT managers
have been heavily dependent upon the old storage model of RAID and
tape being their primary means to store and backup data. As a company
grows, its data needs a place to live as email, applications, platforms
and the advent of e-business operations emphasize consistent availability
IT departments know that without sufficient data
storage, the company goes out of business. Only up until recently
IT staffs have been resorting to what they have known all their
lives by throwing more expensive RAID at their problem, hoping that
their piecemeal solution will halt the progress of data growth.
But in doing so, they add fuel to the fire by not only draining
their annual budgets in a matter of months, but affect the overall
efficiency of the network by increasing the backup window and hiring
additional IT staff to manage the entire chaos.
Tape continues to serve as the primary method
of backup, but without random access capabilities and a long shelf
life, there is no real archive solution present. Does this sound
like an efficient 21st century, e-business?
With the storage industry warming up to NearLine
storage, the storage model is rewritten bringing not only a means
to address growing data requirements, but doing so at a fraction
of the total cost of RAID.