Network Types

Storage Area Network

A Storage Area Network (SAN) or storage system is a computer network that provides access to consolidated, data storage devices. SANs are primarily used to increase the accessibility of storage devices, such as disk drives and library tables, to servers, so that the devices are displayed on the operating system as connected devices locally.

What is Storage Area Network

A Storage Area Network (SAN) is a secure, high-speed data transfer network that provides access to the final storage consolidation, data storage devices. Storage Area Networks are usually made up of hubs, switches, storage components, and storage devices that are interconnected with a variety of technologies, topologies, and protocols.

SANs Networks are the most commonly used storage system architecture used by companies in business-related applications that need high performance and low time. SANs enable organizations to apply more rigorous methodologies and tools for security, data protection, and disaster recovery.

Why do we need to use the SAN Storage Area Network?

While a single server can provide multiple hard disk shared machines, large networks may require more storage than one server can offer. For example, large companies may have several terabytes of data that need to be accessible to multiple Local Area Networks. In this situation, you could set up a Storage Area Network instead of adding more servers. Because only hard drives need to be replaced instead of perfect computer systems, SANs are an effective way to increase network storage

Storage Area Network Architecture

Storage Area Network Architecture is a conceptual combination and logical structure of a network that has the main purpose of transferring data between storage devices and servers and among other storage devices.

SANs architecture is characterized into two types such, storage-centric SAN IT architecture, and network-centric SAN IT architecture.

1. Server Centric IT Architecture

  • In conventional IT architectures, storage devices are normally only connected to a single server. To increase fault tolerance, storage devices are sometimes connected to two servers, with only one server actually able to use the storage device at any one time.
  • In both cases, the storage device exists only in relation to the server to which it is connected. Other servers cannot directly access the data; they always have to go through the server that is connected to the storage device. This conventional IT architecture is therefore called server-centric IT architecture.
  • In this approach, servers and storage devices are generally connected together by SCSI cables.

Limitation

  1. In conventional server-centric, IT architecture storage devices exist only in relation to the one or two servers to which they are connected. The failure of both of these computers would make it impossible to access this data
  2. If a computer requires more storage space than is connected to it, it is no help whatsoever that another computer still has attached storage space, which is not currently used Consequently, it is necessary to connect ever more storage devices to a computer. This throws up the problem that each computer can accommodate only a limited number of I/O cards.
  3. The length of SCSI cables is limited to a maximum of 25m. This means that the storage capacity that can be connected to a computer using conventional technologies is limited. Conventional technologies are therefore no longer sufficient to satisfy the growing demand for storage capacity

2. Storage – Centric IT Architecture and its advantages

  • In storage area networks, storage devices exist completely independently of any computer. Several servers can access the same storage device directly over the storage network without another server having to be involved.
  • The idea behind storage networks is that the SCSI cable is replaced by a network that is installed in addition to the existing LAN and is primarily used for data exchange between computers and storage devices.

Advantages:

  1. The storage area network permits all computers to access the disk subsystem and share it. Free storage capacity can thus be flexibly assigned to the computer that needs it at the time.

Types of Storage Area Network:

The most common Types of Storage Area Network protocols are:

1. Fiber Channel Protocol (FCP). Most used SAN or blockchain description, used in 70% to 80% of the total SAN marketplace. FCP uses Fiber Channel protocols with built-in SCSI commands. Internet Small Computer System Interface (iSCSI). The next largest SAN or block protocol, with about 10% to 15% of the market. iSCSI encloses SCSI commands in an Ethernet frame and then uses the IP Ethernet network for transmission.

2. Fiber Channel over Ethernet (FCoE). FCoE is within 5% of the SAN marketplace. It is similar to iSCSI in that it is enclosed in an FC framework inside the Ethernet database. So like iSCSI, it uses IP Ethernet network for transport.

3. Unstable Memory Express via Fiber Channel (FC-NVMe). NVMe is a protocol interface for accessing flash storage via PCI Express (PCIe) bus. Unlike traditional all-glass architectures, which are limited to one sequential queue, NVMe supports tens of thousands of parallel queues, each with the ability to support tens of thousands of concurrent commands.

Storage Area Network Components

Storage Area Network involves 3 basic components:

1. Server

2. Network Infrastructure

3. Storage

The above elements are classified into the following elements like,

  1. Node port
  2. Cables
  3. Interconnection Devices
  4. Storage Array, and
  5. SAN Management Software

These are explained below.

1. Node port:

In the fiber channel, devices like,

  • Host
  • Storage
  • Tape Libraries are referred to as nodes

Nodes consist of ports for transmission between other nodes. The ports operate in full-duplex data transmission mode via a transmission (Tx) and receive (Rx) connection.

2. Cables:
SAN implements fiber optic cables. Copper cables are used for short-distance connections, and optical cables are used for long-distance connections.

There are 2 types of optical cables: Multi-purpose fiber and Single-mode fiber are as described below.

1. Multi-mode fiber:

It is also called the MMF, because it carries multiple rays of light projected at different angles on the core of the cable at the same time. In MMF transmission, the light beam traveling inside the cable tends to scatter and collide. This collision weakens the signal strength after it travels a certain distance, and is called modal dispersion.

MMF cables are used for distances up to 500 meters due to signal degradation (attenuation) due to modal dispersion.

2. Single-mode fiber:

It is also called SMF, because it carries one beam of light through the fiber core. The small core in the cable reduces the modal dispersion. SMF cables are used for distances up to 10 kilometers due to less attenuation. The SMF is more expensive than the MMF.

In addition to these cables, standard connectors (SC) and Lucent connectors (LC) are commonly used fiber cables with data rates up to 1 Gbps and 4 Gbps, respectively. The small form factor plug (SFP) is an optical transceiver used in optical communication with transmission speeds of up to 10 Gbps.

3. Interconnection Devices:
The commonly used interconnection devices in SAN are:

  1. Hubs
  2. Switches and
  3. Directors

Hubs are communication devices used in fiber implementation. They connect nodes in a loop or star topology.
Switches are more intelligent than hubs. They route data directly from one port to another. They are cheap and their performance is better than hubs.
Directors are larger than switches, which are used to implement data centers. Directors have high fault tolerance and a larger number of terminals than switches.

4. Storage Array:

The primary purpose of a SAN is to provide the host with access to storage resources. SAN repository implementations provide:

  • high availability and surplus,
  • improved performance,
  • business continuity and
  • multiple host connections.

5. SAN Management Software:

This software manages the interface between the host computer, the interconnect device and the storage array. This includes key management functions such as mapping storage devices, switches, and logical SAN partitions, called zoning. It also manages important SAN components such as storage devices and interconnection devices.

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Advantages of Storage Area Network (SAN)

Main advantages of Storage Area Network claimed are the following:

  1. Flexible for many to many connectivities among servers and storage devices with the help of fiber channel hubs and switches.
  2. Up to 10 Km separation between a server and a storage system using appropriate fiber optic cables.
  3. Better isolation capabilities allowing the non-disruptive addition of new servers and peripherals.
  4. Greater performance.
  5. Backup and Online Recovery
  6. Increased disk utilization
  7. Increased I/O performance
  8. Less Number of Server’s are required
  9. Cluster support
  10. Storage Virtualization
  11. Better disk utilization
  12. Elimination of bandwidth bottlenecks associated with LAN-based server storage
  13. No scalability limitations imposed by SCSI bus-based implementations.
  14. High availability
  15. Greater fault tolerance
  16. Centralized storage management.
  17. Faster backups
  18. Global file systems
  19. Rapid data migration
  20. Fault tolerance
  21. Better data security
  22. Improved storage utilization
  23. Greater scalability
  24. Greater Improve application availability such as multiple data paths
  25. Enhanced application performance by offload storage functions or segregating networks.

Application of Storage Area Network (SAN)

SANs are typically used to store data, such as disk arrays, tape libraries, and optical jukeboxes, that can be used on servers so that devices can be displayed in equipment in the operating system. The major applications of Storage Area Network or SAN are in the Applications category, Backup & Data Recovery, etc.

Storage Area Network Benefits:

Using SAN can produce the following benefits:

  • Improving applications available: Storage is independent of applications and can be accessed through a variety of data paths for better reliability, availability, and service delivery.
  • Application performance enhancement: The process is offloaded from the servers and moved into separate servers.
  • Intermediate and integrated planning: Ease of management, development, adaptability, and affordability. Data transfers and remote access: Remote access to data to prevent damage and counter malicious attacks.

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