RAID and SSDs
a Storage Architecture Guide
trust SSD market data?
where are we now
with SSD software?
how fast can your SSD
What were the big
SSD ideas of 2015?
SSDs - the Survive and Thrive Guide
how much flash needed
to replace all enterprise HDDs?
classic article - May 2004 - by Duran Alabi,
VP of Sales and Marketing -
Drivers in Information Storage
Data is unquestionably the
lifeblood of today's digital organization. Storage solutions remain a top
priority in IT budgets precisely because the
protection of data are
vital to business productivity and success. But the role of information storage
far exceeds day to day functions. Enterprises are also operating in an era of
increased uncertainty. IT personnel find themselves assessing and planning for
more potential risks than ever before, ranging from acts of terrorism to network
security threats. A
backup and disaster
recovery plan is essential, and information storage solutions provide the
basis for its execution.
Businesses are also subject to a new wave of regulatory
that directly affects the process of storing, managing and
archiving data. This is
especially true for the financial services and healthcare industries, which
handle highly sensitive information and bear extra responsibility for
maintaining data integrity and privacy.
Although the need for storage is evident, it is not always clear which
solution is right for your organization. There are a variety of options
available, the most prevalent being direct-attached storage (DAS), network-attached
storage (NAS) and storage
area networks (SAN).
Choosing the right storage solution can be as personal and individual a decision
as buying a home. There is no one right answer for everyone. Instead, it is
important to focus on the specific needs and long-term business goals of your
organization. Several key criteria to consider include:
- Capacity - the amount and type of data (file level or block level) that
needs to be stored and shared
- Performance - I/O and throughput requirements
- Scalability - Long-term data growth
- Availability and Reliability
- how mission-critical are your applications?
- Data protection -
- IT staff and resources available
- Budget concerns
|While one type of storage media
is usually sufficient for smaller companies, large enterprises will often have a
mixed storage environment, implementing different mediums for specific
departments, workgroups and remote offices. In this paper, we will provide an
overview of DAS, NAS and SAN to help you determine which solution, or
combination of solutions, will best help you achieve your business goals. |
Ideal for Local Data Sharing Requirements
Direct-attached storage, or DAS, is the most basic level of
storage, in which storage devices are part of the host computer, as with drives,
or directly connected to a single server, as with
RAID arrays or
tape libraries. Network
workstations must therefore access the server in order to connect to the storage
device. This is in contrast to networked storage such as NAS and SAN, which are
connected to workstations and servers over a network. As the first widely
popular storage model, DAS products still comprise a large majority of the
installed base of storage systems in today's IT infrastructures.
|Although the implementation of
networked storage is growing at a faster rate than that of direct-attached
storage, it is still a viable option by virtue of being simple to deploy and
having a lower initial cost when compared to networked storage. When considering
DAS, it is important to know what your data availability requirements are. In
order for clients on the network to access the storage device in the DAS model,
they must be able to access the server it is connected to. If the server is down
or experiencing problems, it will have a direct impact on users' ability to
store and access data. In addition to storing and retrieving files, the server
also bears the load of processing applications such as e-mail and databases.
and slowdowns in data
may occur as server bandwidth is consumed by applications, especially if there
is a lot of data being shared from workstation to workstation.
DAS is ideal for localized file sharing in environments with a single
server or a few servers - for example, small businesses or departments and
workgroups that do not need to share information over long distances or across
an enterprise. Small companies traditionally utilize DAS for file serving and
e-mail, while larger enterprises may leverage DAS in a mixed storage environment
that likely includes NAS and SAN. DAS also offers ease of management and
administration in this scenario, since it can be managed using the network
operating system of the attached server. However, management complexity can
escalate quickly with the addition of new servers, since storage for each server
must be administered separately.
From an economical perspective, the initial investment in
direct-attached storage is cheaper. This is a great benefit for IT managers
faced with shrinking budgets, who can quickly add storage capacity without the
planning, expense, and greater complexity involved with networked storage. DAS
can also serve as an interim solution for those planning to migrate to networked
storage in the future. For organizations that anticipate rapid data growth, it
is important to keep in mind that DAS is limited in its scalability. From both a
cost efficiency and administration perspective, networked storage models are
much more suited to high scalability requirements.
Organizations that do eventually transition to networked storage can
protect their investment in legacy DAS. One option is to place it on the network
via bridge devices, which
allows current storage resources to be used in a networked infrastructure
without incurring the immediate costs of networked storage. Once the transition
is made, DAS can still be used locally to store less critical data.
|NAS: File-Level Data
Sharing Across the Enterprise
Networked storage was developed to address the challenges inherent
in a server- based infrastructure such as direct-attached storage.
Network-attached storage, or NAS, is a special purpose device, comprised of both
hard disks and management software, which is 100% dedicated to serving files
over a network. As discussed earlier, a server has the dual functions of file
sharing and application serving in the DAS model, potentially causing network
slowdowns. NAS relieves the server of storage and file serving responsibilities,
and provides a lot more flexibility in data access by virtue of being
NAS is an ideal choice for organizations looking for a simple and
cost-effective way to achieve fast data access for multiple clients at the file
level. Implementers of NAS benefit from performance and productivity gains.
First popularized as an entry-level or midrange solution, NAS still has its
largest install base in the small to medium sized business sector. Yet the
hallmarks of NAS - simplicity and value - are equally applicable for the
enterprise market. Smaller companies find NAS to be a plug and play solution
that is easy to install, deploy and manage, with or without IT staff at hand.
Thanks to advances in disk drive technology, they also benefit from a lower cost
In recent years, NAS has developed more sophisticated functionality,
leading to its growing adoption in enterprise departments and workgroups. It is
not uncommon for NAS to go head to head with storage area networks in the
purchasing decision, or become part of a NAS/SAN convergence scheme. High
reliability features such as RAID and hot swappable drives and components are
standard even in lower end NAS systems, while midrange offerings provide
enterprise data protection features such as replication and mirroring for
business continuance. NAS also makes sense for enterprises looking to
consolidate their direct-attached storage resources for better utilization.
Since resources cannot be shared beyond a single server in DAS, systems may be
using as little as half of their full capacity. With NAS, the utilization rate
is high since storage is shared across multiple servers.
The perception of value in enterprise IT infrastructures has also
shifted over the years. A business and ROI case must be made to justify
technology investments. Considering the downsizing of IT budgets in recent
years, this is no easy task. NAS is an attractive investment that provides
tremendous value, considering that the main alternatives are adding new servers,
which is an expensive proposition, or expanding the capacity of existing
servers, a long and arduous process that is usually more trouble than it's
worth. NAS systems can provide many terabytes of storage in high density form
factors, making efficient use of data center space. As the volume of digital
information continues to grow, organizations with high scalability requirements
will find it much more cost-effective to expand upon NAS than DAS. Multiple NAS
systems can also be centrally managed, conserving time and resources.
Another important consideration for a medium sized business or large
enterprise is heterogeneous data sharing. With DAS, each server is running its
own operating platform, so there is no common storage in an environment that may
include a mix of Windows, Mac and Linux workstations. NAS systems can integrate
into any environment and serve files across all operating platforms. On the
network, a NAS system appears like a native file server to each of its different
clients. That means that files are saved on the NAS system, as well as retrieved
from the NAS system, in their native file formats. NAS is also based on
industry standard network protocols such as TCP/IP, FC and CIFS.
|SANs: High Availability for
Block-Level Data Transfer|
A storage area network, or SAN, is a
dedicated, high performance storage network that transfers data between servers
and storage devices, separate from the local area network. With their high
degree of sophistication, management complexity and cost, SANs are traditionally
implemented for mission-critical applications in the enterprise space. In a SAN
infrastructure, storage devices such as NAS, DAS, RAID arrays or tape libraries
are connected to servers using
Fibre Channel. Fibre
Channel is a highly reliable, gigabit interconnect technology that enables
simultaneous communication among workstations, mainframes, servers, data storage
systems and other peripherals. Without the distance and bandwidth limitations of
SCSI, Fibre Channel is
ideal for moving large volumes of data across long distances quickly and
In contrast to DAS or NAS, which is optimized for data sharing at the
file level, the strength of SANs lies in its ability to move large blocks of
data. This is especially important for bandwidth-intensive applications such as
database, imaging and transaction processing. The distributed architecture of a
SAN also enables it to offer higher levels of performance and availability than
any other storage medium today. By dynamically balancing loads across the
network, SANs provide fast data transfer while reducing I/O latency and server
workload. The benefit is that large numbers of users can simultaneously access
data without creating bottlenecks on the local area network and servers.
SANs are the best way to ensure predictable performance and 24x7 data
availability and reliability. The importance of this is obvious for companies
that conduct business on the web and require high volume transaction processing.
Another example would be contractors that are bound to service-level agreements
(SLAs) and must maintain certain performance levels when delivering IT services.
SANs have built in a wide variety of failover and fault tolerance features to
ensure maximum uptime. They also offer excellent scalability for large
enterprises that anticipate significant growth in information storage
requirements. And unlike direct-attached storage, excess capacity in SANs can be
pooled, resulting in a very high utilization of resources.
| There has been much debate in
recent times about choosing SAN or NAS in the purchasing decision, but the truth
is that the two technologies can prove quite complementary. Today, SANs are
increasingly implemented in conjunction with NAS. With SAN/NAS convergence,
companies can consolidate block-level and file-level data on common arrays.
Even with all the benefits of SANs, several factors have slowed their
adoption, including cost, management complexity and a lack of standardization.
The backbone of a SAN is management software. A large investment is required to
design, develop and deploy a SAN, which has limited its market to the enterprise
space. A majority of the costs can be attributed to software, considering the
complexity that is required to manage such a wide scope of devices.
Additionally, a lack of standardization has resulted in interoperability
concerns, where products from different hardware and software vendors may not
work together as needed. Potential SAN customers are rightfully concerned about
investment protection and many may choose to wait until standards become
With such a variety of
information storage technologies available, what is the best way to determine
which one is right for your organization? DAS, NAS and SAN all offer tremendous
benefits, but each is best suited for a particular environment. Consider the
nature of your data and applications. How critical and processing-intensive are
they? What are your minimum acceptable levels of performance and availability?
Is your information sharing environment localized, or must data be distributed
across the enterprise? IT professionals must make a comprehensive assessment of
current requirements while also keeping long-term business goals in mind.
Like all industries, storage networking is in a constant state of
change. It's easy to fall into the trap of choosing the emerging or disruptive
storage technology at the time. But the best chance for success comes with
choosing a solution that is cost-correct and provides long term investment
protection for your organization. Digital assets will only continue to grow in
the future. Make sure your storage infrastructure is conducive to cost-effective
expansion and scalability. It is also important to implement technologies that
are based on open industry standards, which will minimize interoperability
concerns as you expand your network.
|From 2007 to 2014 - the
dominant focus and center of SSD accelerator gravity was PCIe SSDs. But the
next chapter of the fast SSD accelerator story looks more like a DIMM|
|What happened in the
SSD market in 2015?|
dominant storage architecture thing has totally flipped. It was already slowly
turning 180 degrees a couple years ago, but it is beginning to be much more
obvious now. SAN is on the decline..."
|Chin-Fah Heoh, StorageGaga - in his reminiscent blog -
reverse wars DAS vs NAS vs SAN (March 2015)|
|micro tiering and micro
One of the trends in computer architecture in recent years is
that new software architectural concepts which deliver sustainable efficiency or
management efficiencies have found it easier to get their benefits established
and recognized at a large scale - as part of big web entities or cloud
But the lessons learned have been duly noted and reapplied to other
use cases. The new architectural ideas are now finding their way into
individual rack scale products too.
|12 key SSD
ideas which emerged or clarified in 2014|
|"Little words can have
with big meanings in the world of SSDs. They affect price, performance,
reliability and user happiness."|
|flash SSD jargon explained|
| "One petabyte of
enterprise SSD could replace 10 to 50 petabytes of raw HDD storage in the
enterprise - and still run all the apps faster and at lower cost."|
|meet Ken and the SSD
|About the Author:- Duran Alabi|
|(The author profile below was correct at the time
this article was originally published. The link above takes you to the author's
linkedin page - which didn't exist at the time - but today is more up to date.)|
Alabi is the vice president of sales and marketing for Xtore, where he is
responsible for the development and implementation of strategic sales and
marketing initiatives. With over 17 years of management experience, he is
ideally positioned to grow the Xtore brand and identify emerging opportunities
for Xtore's wide range of storage solutions.
Mr. Alabi previously served as the vice president of international
sales and marketing for JMR Electronics, a global provider of OEM storage
products, where he was responsible for all aspects of international marketing,
business development and product positioning. His prior professional experience
includes executive sales and marketing positions with Micropal Corporation and
Digital Equipment Corporation. He is a member of the Storage Networking Industry
Association, Fibre Channel Industry Association, RAID Advisory Board and Fibre
Industry Advisory Board.
He is the author of two previously published
articles on the storage networking industry, "Deploying the Right
Multi-Vendor SAN Solution" and "SANs: Not Just for the Big Boys."