What is Storage Area Network
A SAN is a collection of
storage and backup devices connected together through a network that is totally
separated from other servers via a switch. Fibre channel is the high-speed
technology and communications protocol to connect those storage and backup
devices. Fibre channel cables can be of several kilometers and its first 20
meters can be copper wire and if its length is more, then fiber optical
can be used.
A typical SAN consists of a
farm of disk arrays, CD-ROM, tape libraries, etc. interconnected with Fibre
channel and connected to the outside world through a Fibre channel switch or
bridge. The connections inside the boxes can be Fibre channel, SCSI, ATA or any other technology. Connecting all the storage devices into a network needs
a plethora of hubs, bridges, routers, multiplexors, copper to optical
converters, and other relevant devices as we do for a normal communications
facilitates scalability - Any number of storage devices can be added to
store hundreds of terabytes.
SAN reduces down time -
We can upgrade our SAN, replace defective drives, backup our data without
taking any servers offline. A well-configured SAN with mirroring and
redundant servers can bring zero downtime.
Sharing SAN is possible -
As SAN is not directly attached with any particular server or network, a SAN
can be shared by all
SAN provides long
distance connectivity - With Fibre channel capable of running upto 10
kilometers, we can keep our data in a remote, physically secure
location. Fibre channel switching also makes it very easy to establish
private connections with other SANs for mirroring, backup, or maintenance.
SAN is truly versatile -
A SAN can be single entity, a master grouping of several SANs and can
include SANs in remote locations.
SANs are very expensive
as Fibre channel technology tends to be pricier and maintenance requires a
higher degree of skill
Leveraging of existing
technology investments tends to be much difficult. Though SAN facilitates to
make use of already existing legacy storage, lack of SAN-building skills has
greatly diminished deployment of homegrown SANs. So currently pre-packaged
SANs based on Fibre channel technology are being used among the enterprises.
Management of SAN systems
has proved to be a real tough one due to various reasons. Also for some,
having a SAN storage facility seems to be wasteful one.
Also, there are a few SAN
product vendors due to its very high price and very few mega enterprises
need SAN set up.
As it has been found quite
complex, virtualization concept came into picture for the sake of effective and
efficient management of SAN. Virtualization can be defined as an abstracted
management of huge amounts of equipment and data. Virtualization takes all
diverse and large complex storage devices and makes them appear as one Hugh volume.
Presently there are three proven methodologies for achieving SAN
virtualization in the market.
virtualization - This methodology requires a control software program on
every server that accesses the SAN. The main benefits out of this are easy
installation and access. However, if the servers are loaded with different
operating systems, then the control software has to support all of them.
This mechanism seems to be highly beneficial under the situation in which
there is a need for incorporating NAS boxes to the network along with
virtualization - It works in a homogeneous hardware environment, i.e.,
everything has to be from the same vendor.
virtualization - This is the Vicom hardware method, which is in many
pre-configured SANs. It is simply another component of the SAN that sits
between the Fibre channel switch connected to the host servers and another
Fibre channel switch connected to the SAN. The primary benefits out of this
methodology is it can work even in a heterogeneous environment. That is,
multiple servers running on different operating systems can access a
is literally a separate network devoted entirely to storage. Almost all SANs
communicate and connect to servers via a Fibre channel host adopter card and