Brief Introduction to Storage Area Network

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 Hmmm looks like you want to know and understand the so-called SAN(Storage Area Network). For a better understanding, I'm going to split each topic into section vice and without wasting any further time let's start the series with a brief introduction.


In the olden days, storage was available in the form of tape drives, Harddisk, CD, SSD and so on......
As time passes the demand for storage capacity, speed, performance, availability increased and parallelly there was a relevant advancement in the technology. Currently, NVMe is the most widely used technology for storage access.


Storage can be accessed in various ways and below are some of them

1. Local Access

  1. DAS   - Direct Attached Storage 

2. Remote Access

  1. SAN - Storage Area Network where the storage is accessed through storage protocol like SCSI, FCoE, FC, iSCSI, NVMe.
  2. NAS  - Network-attached storage where the mode of access at the file level.  


The main component involved in the SAN is server, san switches, and Storage. Some of the server vendors are Dell, DellEMC, HP, IBM. SAN Switch vendors are Brocade, Cisco ..etc. Storage vendors are Dell, NetApp, HP...

            FIG-1: SAN Connectivity 


   As shown in the above figure a host/server is connected to Storage through SAN switches. The communication happens by using any of the storage protocols like SCSI. 

The server has a Host Bus Adapter(HBA)  which is connected to the switch. When the Host HBA powers on it send FLOGI request to switch then followed by PLOGI.Once the switch assigns the FCID to the host HBA, the host is allowed to access the storage as per the configured "Zoning" in the switch. 

Then Storage also follows the same process of fabric login and when the host wants to access the LUN,
the storage allows as per the configured "Masking" setting.

Now the server can access the data present on the disk and can store required information in the disk.
what happens if the disk fails due to external conditions/ internal failures????
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........................
for this some of the data protection techniques are
  1. RAID - Redundant Array of Independent Disks
  2. Data Replication

Till I come back with the next article stay tuned.Till then bye bye........




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