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What’s iSCSI Storage and How to Plan an iSCSI SAN?

August 9, 2018

Now massive data has been generated everyday which need to be safely stored and economically managed so that they can be available to users when required. Thus there appears various storage systems such as Network Attached Storage (NAS), Internet Small Computer System Interface (iSCSI), etc. Among them, iSCSI storage is a favored new technology that provides high-speed, low-cost, and long-distance storage solution. Here will introduce what’s iSCSI storage and give tips on planning an iSCSI SAN.

What Is iSCSI Storage?

iSCSI is a storage area networking protocol that defines how data is transferred between host systems and storage devices. So iSCSI storage is also known as iSCSI SAN storage, which is a cost-effective alternative to traditional Fibre Channel (FC) SAN. Unlike FC SAN which requires dedicated hardware (FC HBA, FC switch, etc.), iSCSI SAN storage can be built on existing network infrastructure (fiber switch, router, etc.), rather than requiring us to buy additional hardware. Further more, iSCSI is based on block transfer standard, which is more fast and efficient.

iSCSI Storage architecture

(Source: TechGenix)

How Does iSCSI Storage Work?

To understand how iSCSI storage works, we’d better to know iSCSI initiator and iSCSI target. iSCSI initiator is a client component on the host system consuming the storage. It is responsible for initiating requests to and receiving responses from an iSCSI target. iSCSI target is on storage devices providing the storage, which listens and responds to commands from iSCSI initiators. As shown below, iSCSI storage works by transporting block-level data between iSCSI initiator and iSCSI target through the TCP/IP network.

how iSCSI storage works

How iSCSI Storage Works

(Source: VMware)

Why Use iSCSI Storage?

Except for the above mentioned advantages such as cost-saving and high performance, iSCSI storage also offers the following benefits:

 Since iSCSI is run on Gigabit Ethernet network components (Gigabit Ethernet switch, router, etc.), it not only makes it cheaper to adopt but also simplifies the network storage environment
 IT staff requires no extra skill training for dealing with an iSCSI storage. Anyone who is familiar with the TCP/IP technology can easily install and manage the iSCSI SAN
 iSCSI storage is based on TCP/IP which is a universal and non-proprietary technology, therefore various branded network storage devices in iSCSI SAN can work seamlessly together

How to Plan an iSCSI SAN?

iSCSI SAN is suitable for small/medium-sized businesses that have large amounts of data to store and transmit over the network. Here gives some tips on how to plan and configure iSCSI SAN for enterprise network:

First, though iSCSI storage network can run on existing network infrastructure, it is better to place iSCSI traffic on its own VLAN, preferably on a completely separate, gigabit-speed network. This helps to make a redundancy connection for storage data in case of network failure.

Second, you should use enterprise-class, non-blocking, Gigabit Ethernet switch for iSCSI SAN. A consumer-grade switch often does not support wire-speed connections between multiple ports, therefore they may drop packets without warning. For data center applications, 10GbE iSCSI SAN is more future-proofing, so 10GbE switch is preferred.

Lastly, if your servers have single-Gigabit connections to an Ethernet switch for access to disk arrays, they are vulnerable to failure on that link. The best way is to use Multipath I/O (MPIO) technique to create multiple connections from each server's iSCSI initiator to your disk array.


To conclude, iSCSI storage can leverage enterprise’s network infrastructure investments by using standard Ethernet switches and routers to move the data from server to storage. It also enables IP infrastructure to be used for expanding access to SAN storage and extending SAN connectivity across any distance. So organizations requiring data storage security or disaster recovery will benefit a lot from iSCSI SAN.


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