Details Explanation Of SAN Storage Architecture

Details Explanation Of SAN Storage Architecture

This blog explains What is SAN storage how SAN storage works. What are the SAN Storage components and how they connects to each other.

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. Host uses the storage from storage arrays as if its 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 layer. Host, Fabric and Storage Layer. These three layers connects to each other and form an Storage Area Network or SAN network. Each layer has its own functions. We will discuss about their function in coming section.

Below is a very simple architecture diagram of SAN storage which has all of Storage Area Network.

                           

Host Layer Of SAN Storage

Host layer of SAN Storage has servers or host. Hosts are basically a 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 consist of one or more SAN switch. SAN Switch provides a connections points in SAN architecture. All Host connects to SAN switch and Storage Array also connects to same SAN switch. Thus it act as 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 storage area network.

Storage Layer in Storage Area Network

In storage layer of Storage Area Network storage arrays are present where data resides in physical disks. Storage Array consist of physical disk. These disks are grouped logically using special technology called RAID for data protection. These RAID helps in data recovery whenever a disk failure occurs. There various types of RAID type. Depending on requirement specific RAID type is selected for creating raid group. Common RAID type are RAID 5 and RAID 6.

Most of storage arrays has Dual storage processors (SPs) which are the front end of the storage array. These SP has front end IO module which has FC ports. These FC ports connects to SAN switch via FC cables.

Below is an architecture diagram of typical SAN storage which has all components of Storage Area Network with redundant setup.

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 Fabric layer SAN Switch then sends this request to Storage Array. In Storage Array SP receives the request, process it and then sends an acknowledgement back to the host through same path.

For more detail explanation on this topic please watch this YouTube Video. For more such videos on SAN and NAS technology Subscribe to the channel.

             

What Is And How NPV Works SAN Switch

What Is And How NPV Works SAN Switch

In this blog we will discuss what is NPV and how NPV works in SAN switch. NPV sounds similar to NPIV but they are different in terms of their use. Click the link to check what is NPIV and how NPIV works in SAN switch. For all tutorial under SAN switch click here.

What Is NPV In SAN Switch

What is NPV In SAN Switch ? NPV stands for N_Port Virtualization. This is SAN Switch level features. NPV enabled switch act as a proxy switch and bypass all FC services request to its up-link switch. NPV is a Cisco Specific term other vendor calls it as different name. In terms of Brocade its called as Access Gateway Switch.

How NPV Works In SAN Switch

In order to understand how NPV works we should understand what happens when a new switch connects to fabric. In usual case when a SAN switch is connected to a fabric its gets Domain ID and participate in Fabric Services like assigning FCID to initiator.

Now in case of NPV if the SAN switch is NPV enabled then it will not have any Domain ID and does not participate any FC services. Whatever Device connected to NPV enabled switch such as host , switch or UCS or any device gets FC services from its up-link switch.

Use Of NPV SAN Switch Network

There are various ways to use NPV in SAN switch. Below are some examples where we can use NPV. One of the rare use of NPV where fabric requires more then 239 switches or there is a limitation of Domain ID. For each switch in a fabric it requires a domain ID. Now as the fabric grows number of SAN switch also grows and as a result Domain ID also grows. If the number of switches reaches to 239 domain id also reaches to 239. In such scenario if more switches requires then NPV is a solution to add more switches to fabric.

Another practical use of NPV is multi vendor SAN switches in same fabric. If you have a SAN fabric with switches of multiple vendor then NPV is necessary. For example you can connect a Cisco Core switch with brocade SAN switch. Note both switches must be interoperability mode.

You can also use NPV for migrating SAN switches from one vendor to another. We can use NPV as pre deployment stage for SAN switch migration from one vendor switch to another. For more details you can visit the below link.

Below is an YouTube videos which have details explanation of NPV features and its uses. Subscribe the channel for more such videos on SAN switch training.


       

What Is And How NPIV Works In SAN Switch

What is NPIV In SAN Switch

NPIV is SAN switch port level virtualization feature. NPIV stands for N-Port ID Virtualization. NPIV allows multiple initiator to logged in to same single physical target port. NPIV is mostly used SAN network where ESX Host, Blade Server and UCS deployment are present.

How NPIV Works In SAN Switch

In order to understand how NPIV works in SAN switch first lets understand how a SAN connectivity works without NPIV. In usual case one initiator or host is connected to single port of SAN switch.
During FLOGI process the switch assign a FCID to initiator and the initiator is logged in to switch port.

Below is one diagram which has simple connectivity of two server to SAN switch. where two server use two ports of SAN switch to logged in.

Now in case of NPIV multiple initiator tries to login to same single physical port of SAN switch. If SAN switch port is NPIV enabled then switch port accepts request from each initiator and assign a FCID to each initiator. Once all initiator receives a FCID all of them are logged to to same physical port.

Below diagram explains the connectivity and uses of NPIV in SAN switch network. Here compute system which is similar to blade server of ESX host which has single physical HBA which connects to single SAN switch port. In back-end the compute system has multiple nodes which shares same common physical HBA. Each node of compute system has a virtual HBA having virtual WWPN.

During FLOGI Process each virtual WWPN send request to same SAN switch port and if the SAN switch port is NPIV enabled it accepts all request and assign FCID to each node or initiator. This way multiple initiator logged in same SAN switch port.

Where We Use NPIV In SAN switch

There are various uses of NPIV in SAN network but below are most common use of NPIV.
If your environment has ESX, UCS, or Blade Server Deployment then definitely your SAN switch ports are NPIV enabled.

Second common use of NPIV is that it allows masking of LUN to individuals VMs. It means if you have multiple VMs in ESX host then you can do zoning between the VMs WWPN and Storage array. Then you can share individual LUNs to particular VM.

Third common use is that it reduce messy cable connectivity of SAN network. If you have large number of server then lot of cable connection is require between server and switch which makes difficult for Data Center admin to perform physical maintenance activity. As NPIV reduce the number of connection between server and switch physical management of Data center make simpler.
Below is one of the videos which explains the purpose of NPIV and how it works. Subscribe to YouTube Channel for such videos.