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This video explains What is SAN storage how SAN storage works. What are the SAN Storage components and how they connect to each other?
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What is SAN Storage?
SAN storage stands for Storage Area Network. A SAN is a specialized high‐speed network of storage devices and SAN switches connected to computer systems called as Host or Server via Fiber optic cables. A host uses the storage from storage arrays as if it is local to Host. As the data communication happens via fiber optics the data speed is high in comparison to NAS storage.
Components Of SAN Storage
SAN Components can be divided into 3 layers. Host, Fabric and Storage Layer. These three layers connect to each other and form a Storage Area Network or SAN network. Each layer has its own functions. We will discuss their function in the coming section.
Host Layer Of SAN Storage
The host layer of SAN Storage has servers or hosts. Hosts are basically hardware having its own resources like CPU, Memory, Disk storage and an Operating system running on it. Along with these, it has also dual HBA card which connects to the Fabric Layer of SAN Network.
What is Fabric In SAN Storage
Fabric layer or a Fabric of SAN storage consists of one or more SAN switches. SAN Switch provides connections points in SAN architecture. All Host connects to SAN switch and Storage Array also connects to the same SAN switch. Thus it acts as a mediator between Host and Storage.
Typical SAN network has two fabric for high redundancy. In case if one Fabric goes down then other fabric takes care of the data flows in the storage area network.
Storage Layer in Storage Area Network
In the storage layer of Storage Area Network, storage arrays are present where data resides in physical disks. Storage Array consists of a physical disk. These disks are grouped logically using a special technology called RAID for data protection. These RAID helps in data recovery whenever a disk failure occurs. There various types of RAID types. Depending on requirement specific RAID type is selected for creating a raid group. Common RAID types are RAID 5 and RAID 6.
Most of the storage arrays have Dual storage processors (SPs) which are the front end of the storage array. This SP has a front end IO module that has FC ports. These FC ports connect to SAN switch via FC cables.
How SAN Storage Works
When a host from a host layer wants to access a storage device on the SAN, it sends out a block‐based access request for the storage device. SCSI commands are encapsulated into FC packets. Then the Host HBA transmits the FC request to the Storage layer via Fabric.
From the Fabric layer, SAN Switch then sends this request to Storage Array. In Storage Array, SP receives the request, processes it and then sends an acknowledgment back to the host through the same path.