storage area network
DESCRIPTION
TRANSCRIPT
STORAGE AREA NETWORK
Submitted by,
Neha agarwal
DEFINITION
A SAN (Storage Area Network) is a network designed to transfer data from servers to targets, and it is alternative to a directly attached target architecture, or to a DAS architecture
Additional definitions of a SAN imply that the SAN should also be highly performing, and should be such to enable storage devices to communicate with one another and with computer systems
SAN ARCHITECTURE
Storage is accessed at block level not at file level
Very high performances
Storage is shared Good management
tools Interoperability
issues
Storage Area Network (SAN)
DatabaseServers
BlockStorageDevices
Fibre Channel
SAN
Clients
LAN
DIFFERENT TECHNOLOGIES
Multiple technology can be used when building a SAN; traditionally the dominant technology is Fiber Channel, but IP based solutions are also quite popular for specific applications
The concept of SAN is also independent from the devices that are attached to it. Can be disks, tapes, RAIDs, file servers, or other
SAN AND NAS: NETWORK AND NODE
SAN vs NAS: while a SAN is a network connecting storage subsystems, the NAS is a storage subsystem, making use of a general purpose network.
The SAN is an extension of the disk channel outside the server, while the NAS is a disk subsystem connected to the servers, in most cases via an IP network.
HARD DRIVES The basic storage element is an Hard Drive. They
are made into complex devices composed of platters, heads, cylinders and tracks
File systems arrange files into sectors so that they can be stored and retrieved
The File system usually deals with clusters of blocks and uses a FAT (File Allocation Table) to map a file to the sectors
SAN VIRTUALIZATION
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.
TYPES OF SAN VIRTUALIZATION
Host-based 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.
Storage-based virtualization - It works in a homogeneous hardware environment, i.e., everything has to be from the same vendor.
A SAN appliance virtualizes storage and has the effect of converting various storage devices into one big disk. This big virtual disk stores terabytes of data that can allocate storage to different applications quickly and painlessly.
SAN SUPPORTED TOPOLOGIES: POINT TO POINT
Point to point is the simplest topology for very limited connectivity needs
It guarantees in order delivery and full bandwidth access
The application can handle any multipath connectivity to a set of disks in case this is provided, since no other elements are present in this topology
TX TX
RX RX
SAN SUPPORTED TOPOLOGIES: ARBITRATED LOOP Designed to scale to a limited number of nodes (up to 127) Low cost (no interconnecting devices needed) Arbitration protocol is designed to manage media sharing
across nodes; may be disruptive when a node gets added/removed from loop and loop initialization protocol kicks in
A arbitrating hub can be used instead of a distributed protocol
Each node can be a server or a storage device
SAN SUPPORTED TOPOLOGIES: SWITCHED FABRIC
In a switched fabric topology, switching element get added to the nodes to allow interconnections via point-to-point links
Extended number of devices (potentially thousands) and greater distances can be achieved
Scalable, robust and reliable architecture, but the cost of the interconnection devices adds on
Switched Topology
BlockStorageDevices
Fibre Channel
SAN
SUMMARY
What is a SAN Basic Building Blocks of a SAN A zoom into the Storage Architectures SAN elements and architecture FIBRE CHANNEL
FIBER CHANNEL AND THE OTHERS
The Fibre Channel (FC) is used to develop practical, inexpensive, means of quickly transferring data between workstations, supercomputers, desktop computers, storage devices, displays and other peripherials.
Long cable length up to 10 km. Transfer speeds up to 2 gbps. Data must be sent through frames. Used as a backbone for most commercial
networks
SUMMARY
What is a SAN Basic Building Blocks of a SAN A zoom into the Storage Architectures SAN elements and architecture Basic Protocols and Mechanisms Advantages and disadvantages
SAN ADVANTAGES SAN Architecture facilitates scalability - Any number of
storage devices can be added to store hundreds of terabytes.
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 up to 10 kilometers, we can keep our data in a remote, physically secure location.
SAN is truly versatile - A SAN can be single entity, a master grouping of several SANs
SAN DISADVANTAGES
SANs are very expensive as Fibre channel technology tends to be pricier and maintenance requires a higher degree of skill .
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.
CONCLUSION
SAN 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 switch.