Storage developments have opened up the possibility that true data
sharing might just, one day, be a possibility
Nick EnticknapTrue data sharing - where any workstation can access any
corporate data, irrespective of what it is stored on, what database
it is held in, and what the server operating system is - is still a
vision. Or, as EMC UK marketing manager Nigel Ghent puts it: 'True
sharing of information and data is perhaps the vision beyond the
vision.' But we are getting closer?
Only a few years ago, it seemed impossible. In the first half of
the last decade, the traditional storage paradigm saw files held on
disk attached to a specific server, stored in a format determined
by the operating system, and usually held in a proprietary database
management system. Data could only be accessed by a PC connected to
that server, and equipped with the necessary software.
Storage developments since then have opened up the prospect of
real data sharing as a realistic, albeit distant, goal. The first
advance was the ability to share storage subsystems between
heterogeneous servers. Typically this was done on the basis of
partitioning the subsystem, where one server would be allocated
part of the storage, and a second server the other part. Neither
server could access the other's data, even though it was all stored
on the same device.
One vendor took this concept further, and introduced a limited
form of true data sharing. That was Encore, which introduced its
Infinity SP subsystem in early 1995. This was the pioneer of the
modern type of mainframe disk subsystem, with its own processors
and Unix operating system, allowing the development of bespoke
storage applications. It took IBM until 1999 to offer its mainframe
users a disk subsystem with similar flexibility.
Technically, the main limitation of the Infinity SP was that
data sharing was only possible with flat files, and not with
database files. But the main reason why Infinity only sold in small
numbers was commercial. Encore had no presence in the storage
market, and never developed the marketing clout to build one.
As a result, its storage operation was eventually taken over by
Sun Microsystems, which re-engineered and rebadged the Infinity SP,
and now sells the evolved version as the A7000.
Sun's interest in Encore arose because it was trying to develop
its own storage operation as an independent entity, rather than a
division which existed to produce disk systems for Sun servers and
workstations. Infinity seemed an ideal product to try to compete
with IBM, EMC, and co in the mainframe market. But events overtook
Sun before it really got started. The two important developments of
the late '90s were, first, the arrival of Fibre Channel as an
interconnect technology to replace SCSI, and second, the arrival of
the storage area network, or San.
Sun quickly appreciated that this was the direction it had to go
in, and concentrated on building up capability in these two areas.
And very effectively, too: Sun had shipped over 3 petabytes of
Fibre Channel storage by the end of 1999.
As a result, the concept of data sharing took a back seat. Other
developments contributed to this, notably the arrival of
replication technologies, such as StorageTek/IBM Snapshot, and
EMC's SRDF and TimeFinder. Do you need data sharing, with all its
complexity, when you can rapidly make copies of any data you want,
and ship it quickly over fibre optic links to whoever wants it?
The answer, according to Mercury Computer Systems, was 'yes'.
Mercury developed a product called SANergy, which allows file
sharing with the necessary data locking between heterogeneous
clients over a San. The product found a ready market, and has now
sold into 3000 organisations worldwide.
The main European reseller of SANergy is Sagitta Performance
Systems, which has over 100 customers in the UK alone. According to
Sagitta managing director Andy Norman, most of the sales have been
for niche applications - 'video and non-linear editing
companies'.
He continues: 'The implementations today are mainly niche
companies like BSkyB and Printcraft. They are building Sans for
special functions, not for the enterprise. There are several
reasons for that. Sky, for example, was keen to employ a new
architecture, and was prepared to take the risk - they are a
classic early adaptor.'
Last December, SANergy was bought from Mercury by Tivoli. Tivoli
is keen to develop the product into an enterprise data sharing
tool, and is taking a number of steps to achieve that.
First, it has repackaged the product so that, instead of being
for one operating system (NT or Apple Mac or Unix), the same
product supports all three. Second, Tivoli is extending the support
to additional platforms and providing additional file system
support.
Then, according to Tivoli Storage Management products manager
Karen Dutch: 'We are putting a solution together - a combination of
SANergy file sharing and Tivoli Storage Manager to do Lan - and
server-free backup, restore, archiving, and HSM. Again in a
heterogeneous environment - it doesn't matter what type of disks
you've got, anything from JBODs, or mid range server disk, up to
the most intelligent subsystem.'
All of these moves take the existing product and develop it to
be more widely useable. The next step, known internally as the
Storage Tank project, is more radical.
According to Dutch: 'We are looking to deliver in 2001 a brand
new file system oriented towards enterprise San users. It will be a
combination of what SANergy file sharing offers and a brand new
file system, with features such as life cycle management. So it is
not just file sharing; there will be policies to determine where a
file should be placed, for backing up files, and for transferring
files to tape. It is an extension of file sharing with full life
cycle management.'
How will this work? IBM Worldwide SAN programme director Scott
Drummond explains. 'The idea is data sharing by translating every
byte of I/O into a common format, and then converting it into the
form required by the operating system in question.' He adds: 'We
have a prototype working today; the work that remains is to improve
performance.' Tivoli plans to release this product, which will be
known as Tivoli Data Management, next year.
Today, as HDS San and high availability solutions manager
Vincent Franceschini puts it: 'The promise of any data, anywhere,
any time is unrealistic.' But developments such as SANergy and
Tivoli Data Management are bringing the goal closer, by moving data
sharing from being a niche application, to an enterprise-wide
capability. There is some way to go yet, especially as Sans
themselves are still in their infancy, but the new storage world is
visibly taking shape.l
Case study: BSkyB
BSkyB uses SANergy to create all its graphics for programmes on
all the Sky television news, film and ports channels. The company
found that the immense quantities of bytes needed for 3D images
overwhelmed the IT infrastructure, which consisted of an Ethernet
network with a Silicon Graphics host server.
According to visual effects supervisor Dave Sedgwick: 'If
someone needed to work on a different workstation it would take
longer to move the data than it would to complete the project. The
whole process was very time-consuming and would leave us with very
tight deadlines.'
Something more powerful was needed, and Sky found the answer in
a San using a Gadzoox Gibraltar hub and SANergy file sharing
software, put together by Sagitta Performance Systems. The storage
is used by four Silicon Graphics Unix and three NT
workstations.
Now, says Sedgwick, 'our 3D operators can work from any
workstation, any time, and have direct access to the data they
need.'
Case study: Printcraft
Printcraft is a digital pre-press company based in Dublin whose
business, among other things, includes printing Microsoft technical
manuals. Like BSkyB, Printcraft used to rely on an Ethernet Lan,
but found it needed more disk capacity and faster file sharing
speeds. The necessity to use the same workstation to complete
projects was again a major limitation.
According to general manager Julian McDermott: 'We basically
needed an entirely new, high-end installation that would provide us
with excellent storage capacity and scaleability in preparation for
future growth and centralised storage.'
Sagitta Performance Systems again provided the solution - a San
using two Sagitta Fibre Storage Systems and a Gadzoox Capellix
switch, shared between 16 workstations (12 Macs and four NTs).
SANergy software again provides the necessary file sharing
capability, allowing desktop publishing operators instant access to
all centrally held files.
According to McDermott: 'The new San environment has allowed us
to work from any computer, and has enabled us to achieve far more
in less time.'