Storage Area Network

A Storage Area Network (SAN) is a specialized, high-speed network that provides block-level network access to storage. Storage area networks (SANs) are also referred to as network behind the server and historically developed out of a centralized data storage model, but with its own data networks. A SAN is, at its simplest, a dedicated network for data storage. In addition to storing data, SANs allow for the automatic backup of data, and the monitoring of the storage as well as the backup process .A SAN is a combination of hardware and software .SANs are typically composed of hosts, switches, storage elements, and storage devices that are interconnected using a variety of technologies, topologies, and protocols. SANs may also span multiple sites.


Use Of Storage Area Network

Simply stated, a SAN is a network of disks that is accessed by a network of servers. There are several popular uses for SANs in enterprise computing. A SAN is typically employed to consolidate storage. For example, it's common for a computer system, such as a server, to include one or more local storage devices. But consider a data center with hundreds of servers, each running virtual machines that can be deployed and migrated between servers as desired. If the data for one workload is stored on that local storage, the data might also need to be moved if the workload is migrated to another server or restored if the server fails. Rather than attempt to organize, track and use the physical disks located in individual servers throughout the data center, a business might choose to move storage to a dedicated storage subsystem, such as a storage array, where the storage can be collectively provisioned, managed and protected.



A SAN can also improve storage availability. Because a SAN is essentially a network fabric of interconnected computers and storage devices, a disruption in one network path can usually be overcome by enabling an alternative path through the SAN fabric. Thus, a single cable or device failure doesn't leave storage inaccessible to enterprise workloads. Also, the ability to treat storage as a collective resource can improve storage utilization by eliminating "forgotten" disks on underutilized servers. Instead, a SAN offers a central location for all storage, and enables administrators to pool and manage the storage devices together.

How It Works ?

A SAN is essentially a network that is intended to connect servers with storage. The goal of any SAN is to take storage out of individual servers and locate the storage collectively where storage resources can be centrally managed and protected. Such centralization can be performed physically, such as by placing disks into a dedicated storage subsystem like a storage array. But centralization can also be increasingly handled logically through software  such as VMware v SAN which relies on virtualization to find and pool available storage.

By connecting the collective storage to servers through a separate network  apart from the traditional LAN storage traffic performance can be optimized and accelerated because the storage traffic no longer needs to compete for LAN bandwidth needed by servers and their workloads. Thus, enterprise workloads can potentially get faster access to astonishing volumes of storage. A SAN is generally perceived as a series of three distinct layers: a host layer, a fabric layer and a storage layer. Each layer has its own components and characteristics.

  1. Host layer. The host layer represents the servers that are attached to the SAN. In most cases, the hosts servers are running enterprise workloads, such as databases, that require access to storage. Hosts typically employ traditional LAN  Ethernet  components to enable the server and its workload to communicate with other servers as well as users. However, SAN hosts also incorporate a separate network adapter that is dedicated to SAN access. The network adapter used for most FC SANs is called a host bus adapter (HBA). As with most network adapters, the FC HBA employs firmware to operate the HBA's hardware, as well as a device driver that interfaces the HBA to the server's operating system. This configuration allows the workload to communicate storage commands and data through the operating system to the SAN and its storage resources. FC is one of the most popular and powerful SAN technologies available, but other broadly accepted SAN technologies include InfiniBand along with iSCSI. Each technology poses its own array of costs and tradeoffs, so the organization must carefully consider its workload and storage needs when selecting a SAN technology. Ultimately, the host, fabric and storage layers must share the same SAN technology.
  2. Fabric layer. The fabric layer represents the cabling and network devices that comprise the network fabric that interconnects the SAN hosts and SAN storage. SAN networking devices within the fabric layer can include SAN switches gateways, routers and protocol bridges. Cabling and the corresponding ports of SAN fabric devices can employ optical fiber connections for long range network communication or traditional copper based cables for shore range local network communication. The difference between a network and a fabric is redundancy: the availability of multiple alternate pathways from hosts to storage across the fabric. When a SAN fabric is constructed, multiple connections are generally implemented to provide multiple paths. If one path is damaged or disrupted, SAN communication will use an alternative path.
  3. Storage layer. The storage layer is comprised of the various storage devices collected into various storage pools, tiers or types. Storage typically involves traditional magnetic HDDs but can also include SSDs along with optical media devices, such as CD and DVD drives, and tape drives. Most storage devices within a SAN are organized into physical RAID groups that can be employed to increase storage capacity, improve storage device reliability or both. Logical storage entities, such as RAID groups or even disk partitions, are each assigned a unique LUN that serves the same basic purpose as a disk drive letter, such as C or D. Thus, any SAN host can potentially access any SAN LUN across the SAN fabric. By organizing storage resources and designating storage entities in such a manner, an organization can permit which host can access specific LUNs, enabling the business to exert granular control over the organization's storage assets. There are two basic methods for controlling SAN permissions: LUN masking and zoning. Masking is essentially a list of the LUNs that are unavailable to or shouldn't be accessed by a SAN host. By comparison, zoning controls host access to LUNs by configuring the fabric itself, limiting host access to storage LUNs that are in an approved allowed SAN zone.
How to set SAN ?


To integrate all components of the SAN, an enterprise first must meet the vendor's hardware and software compatibility requirements:
  • host bus adapters (firmware version, driver version and patch list);
  • switch (firmware); and
  • storage (firmware, host personality firmware and patch list).

Then, to set up the SAN, you need to do the following:

  1. Assemble and cable together all the hardware components and install the corresponding software.
    1. Check the versions.
    2. Set up the HBA.
    3. Set up the storage array.
    1. Change any configuration settings that might be required.
    2. Test the integration.
      1. Test all the operational processes for the SAN environment, including normal production processing, failure mode testing and backup.
    3. Establish a performance baseline for every component as well as for the entire SAN.
    4. Document the SAN installation and operational procedures.

    Comments

    Post a Comment

    Popular posts from this blog

    Introduction To Memory Management

    Image
    Memory management is the functionality of an operating system which handles or manages primary memory and moves processes back and forth between main memory and disk during execution. Memory management keeps track of each and every memory location, regardless of either it is allocated to some process or it is free. It checks how much memory is to be allocated to processes. It decides which process will get memory at what time. It tracks whenever some memory gets freed or unallocated and correspondingly it updates the status.   Main Memory point out to a physical memory that is the internal memory of the computer. The word main is used to acclaim it from external mass storage devices such as disk drives. Main memory is also known as RAM. The OS is able to change only data that is in main memory. Coming as a result, every program we run and every file we access must be attended from a storage device into main memory. All the programs are loaded in the main memory for implementation. Some
    Read more

    Virtualization

    Image
      What is virtualization?   Virtualization is that the creation of a virtual instead of actual version of one thing, like associate degree. Software package, a server, a device or network resources. Virtualization uses software package that simulates hardware practicality to make a virtual system. These apply permits IT organizations to work multiple in operation systems, quite one virtual system and numerous applications on one server. The advantages of virtualization embrace bigger efficiencies and economies of scale. OS virtualization is that the use of software package to permit a chunk of hardware to run multiple software package pictures at identical time. The technology got it’s begin on mainframes decades a gone, permitting directors to avoid wasting expensive process power. Why we need virtualization? While many look at virtualization as the cloud, in reality the cloud is just a part of virtualization. The most important function of virtualization is the capability of
    Read more

    Research Paper Writing

    Image
    A research paper is an documentation in which you explain what you have learned after exploring your topic in depth. In a research paper, you include information from sources such as books, articles, interviews, and Internet sites. You also use your own ideas, knowledge, and opinions. Most of your paper (as a rule of thumb, at least 80%) must be in your own words.  The goal of a research paper is to bring together different views, evidence, and facts about a topic from books, articles, and interviews, then interpret the information into your own writing. It's about a relationship between you, other writers, and your teacher/audience.  A research paper will show two things: what you know or learned about a certain topic, and what other people know about the same topic. Often you make a judgment, or just explain complex ideas to the reader. The length of the research paper depends on your teacher's guidelines. It's always a good idea to keep your teacher in mind while writing
    Read more