With e-business and compliance inflating storage
requirements, network attached storage and storage area networks
are evolving to help businesses scale up.
The number of transactions channelled through the internet is
increasing daily.
Web-based transactions and e-mail have to be stored and managed,
which means that a lot of these companies and branch offices are
finding their traditional storage systems have to be increased more
often and managed more rigorously.
As this influx of data increases, company managers are finding
new ways to analyse the information, which creates even more data.
To add to the problem, the deletion of files is also becoming less
of an option as regulatory bodies begin to dictate data retention
policies.
The challenge is to find some way to scale up storage in an
elegant fashion rather than just hanging more discs onto every
server.
Pat Lee, senior product manager at SME data storage specialst
EMC Insignia, said, "About five years ago people had a reseller
helping them install a server that had probably 80Gbytes of SCSI
storage. In the smaller business of under 50 users this may have
held their mail server, file server and database server.
"Today, they would have replaced the server with a bigger
server, or several servers, directly attached to yet more storage.
Even then, with the exponential growth in data this would soon
become limiting.
"The reseller or value-added reseller does not want to have to
tell the customer to buy yet another server because the current
ones cannot take the loadings, so they are looking at other ways to
increase storage."
Lee suggests that it is time to switch from direct attached
storage and make disc space available through a network attached
storage (Nas) appliance or to consider a storage area network
(San).
Robin Burke, research vice-president at Gartner, said that such
a strategy could not only make storage more flexible but more
economical. "With direct attached storage or with just a bunch of
discs you are probably only using about 35% to 45% of the available
storage space.
"When you go to a San or Nas you have the ability to increase
that efficiency to 80% to 90% without too much trouble - assuming
you set it up right. For small-to-medium-sized enterprises who are
typically watching their budgets, it allows them to make more
efficient use of the storage they own."
The advantage of network-attached disc systems is that the
unpredictable growth of e-mail storage and databases can be managed
much better and with greater reliability. The problem is how to
sell the idea to the business.
Lee has seen growing interest in entry-level storage systems. He
said businesses do appreciate that when a disc fails it should not
bring down the system, and that the system will scale up as its
needs increase. "In companies of over 100 users I am starting to
see more penetration of entry-level Sans, and we are starting to
see the penetration of entry-level Nas boxes at the lower end of
the market with upwards of 20 users."
What appears to be happening is that the major suppliers are
selling a full range of storage products, from entry-level Nas to
ultra high-end Sans.
Graham Titterington, principal analyst at Ovum, has observed
this change in the market. At one time the Nas and the San camps
were very separate. "A few years ago if you wanted Nas you went to
Network Appliance and if you wanted San you went to EMC. Now EMC
also sells Nas and Network Appliance offers Sans.
"The market is much more blurred and everybody seems to be
selling everything. We are even seeing the growth of mixed Nas and
San systems," he said.
The ability to mix or link Sans and Nas is primarily due to the
development of iSCSI (Internet Small Computer System Interface).
This brings Ethernet-based standards to what was previously a
proprietary protocol market.
The ability to use IP networks simplifies installation and
reduces installation costs. "iSCSI is cheaper, more flexible and
more accessible. You may not get the same bandwidth, but there is
plenty of headroom for most people," Titterington said. "You are
not going to buy Nas if one disc will do, but if you need to move
to the next level for scalability you have to consider the network
technology - and that is invariably IP so iSCSI offers the simplest
route."
The arrival of iSCSI has also increased Microsoft's interest in
supporting network storage. Ewan Dalton, technical architect at
Microsoft, said, "Historically, the official Microsoft position was
that San and Nas systems may well work with Exchange but it was not
a Microsoft-supported configuration.
"That changed about two years ago when the iSCSI standard
started firming up. As a result we now have specific support for
quite a number of iSCSI-based storage devices."
Dalton emphasised that support is only offered if the hardware
used is certified by Microsoft's Windows Hardware Quality Labs.
Microsoft cannot be sure that all storage systems implement the
controls that ensure that discs are written in the way that
Exchange expects it to be done, Dalton said.
"We have to be confident that a system works as advertised and
therefore is not going to corrupt data. Exchange is pretty I/O
intensive and we do not know whether a cheap adaptor is going to
mangle that data or not.
"If you go for a higher-end iSCSI card that has been through the
Windows Labs testing, we are confident that the hardware will be
reliable under stress and that the drivers that support it have
been written in an appropriate way."
Despite Dalton's caveat, Exchange is being used on non-certified
systems quite successfully. The main point is that Microsoft will
not take responsibility if things go wrong on one of these systems.
This would be a problem if a partner company insisted on best
practices to satisfy its compliance requirements.
A lot of the compliance demands that have hit larger enterprises
do not impinge directly on SMEs. However, SMEs often want to do
business with large corporates or public sector organisations.
And according to Hugh Jenkins, enterprise marketing director at
Dell UK, this will result in a trickle down of compliance
requirements, as inter-supplier agreements and contracts
increasingly demand that businesses in their supplier networks
cover themselves by improving their ability to archive and retrieve
e-mail transactions.
Jenkins predicts that the move of e-mail from the personal
communications sphere into the business world will increase the
desire for reliable, scalable storage.
"As a society we are starting to get more litigious and if you
do get embroiled in a legal case the things that are going to get
looked at are the e-mail conversations that took place between the
disputing entities. So you will have to have that stored and easily
retrievable.
"Larger organisations know this and many are being made to
comply. Small but forward-thinking organisations will ensure they
are able to play on the same playing field, especially if they are
part of the supplier network."
According to figures from analyst firm IDC, Dell is the fastest
growing supplier in the Nas market, with an increase in revenues in
the fourth quarter of last year of 65%.
Jenkins said some of the drivers of this growth have centred
around e-mail, which is obviously creating a need for more storage
but also fuels demands for greater control of that data.
"There is a growing realisation that the e-mails have to be
stored securely and not left on desktop systems. There needs to be
a centralised mechanism where it is regularly archived and stored
away so that it can be retrieved in the face of either litigation
or increasing compliance requirements," he said.
Both San and Nas appliances can help because they treat their
attached discs as though they are a single storage space. Data is
stored wherever space allows and new discs can be hot-plugged into
the array without having to bring the system down.
Where the two systems differ is in the way data is stored. Nas
is just like a conventional disc system storing everything in a
file format. San technology was designed more for database-like
content and works on a more transactional basis by storing blocks
of data, such as a single record in a database table.
A major advantage of centralising data storage is the ease with
which data can be shared. In the same way that collaborative
software is helping to create new working environments, the
data-sharing possibilities of Nas and San systems are allowing more
departments to share information for analytical purposes.
Now suppliers are looking at combining Nas and San systems to
gain the best of both worlds. This is currently targeting high-end
users but change is coming to the lower end.
Paul Hickingbotham, solutions manager at storage supplier
Hammer, said, "iSCSI is a very good way to allow San and Nas to be
mixed in a single solution. But it is at a critical stage where,
although we are seeing a big increase in iSCSI sales, it is not yet
fully adopted and trusted as an architecture."
He expects 10Gbyte network hardware to start to become more
affordable and attractive to smaller businesses later this year or
early next year, but said there is a lot of sense in using iSCSI on
current networks.
Although a Fibre Channel San is a very good idea for high-end
data centres it is still too expensive for the SME, especially when
adding a back-up strategy. In Hickingbotham's experience, the
traditional San and Nas technologies do not really help address
this, whereas IP systems such as iSCSI mean the technology can be
treated in a similar way to SQL databases and their disaster
recovery strategy.
The use of Nas and San in smaller business is still in its
infancy and Gartner said it falls below their radar. But this will
soon be changing.
Burke said, "If you look at the key players in the storage
market you find that about two years ago the light clicked on and
almost everybody announced programmes at the same time to target
the SME market. They had run out of expansion in the high and
mid-ranges and had to increase their market scope.
"Now they are pretty active and I guess once we have seen a few
more quarters of the low-end products we will be able to get a
better feel for it."
Glossary of storage terms
Network-attached storage
A server that is dedicated to file sharing, Nas does not provide
any of the activities that a server in a server-centric system
typically provides, such as e-mail, authentication or file
management. Nas allows more hard disc storage space to be added to
a network that already utilises servers, without shutting them down
for maintenance and upgrades.
With a Nas device, storage is not an integral part of the
server. Instead, in this storage-centric design, the server still
handles all of the processing of data, but a Nas device delivers
the data to the user. A Nas device does not need to be located
within the server, but can exist anywhere in a Lan and can be made
up of multiple networked Nas devices.
Storage area network
A San is a high-speed sub-network of shared storage devices. A
San's architecture works in a way that makes all storage devices
available to all servers on a Lan or Wan. As more storage devices
are added to a San, they too will be accessible from any server in
the larger network.
Because stored data does not reside directly on any of the
servers on the network, server power is utilised for business
applications, and network capacity is released to the end-user.
iSCSI
iSCSI (Internet Small Computer System Interface) is an IP-based
standard for linking data storage devices over a network and
transferring data by carrying SCSI commands over IP networks. iSCSI
is important to San technology because it enables a San to be
deployed in a Lan, Wan or metropolitan area network.