Difference between NFS and iSCSI

In today's world, sharing of data is quite common. Basically, it is the process of sharing data or files written by an individual or a group of people and then it is available to multiple applications or websites and read by others. Both iSCSI and NFS are used for file sharing. However, both terms have some differences. They both provide different data-sharing semantics. Though for VM live migration, load balancing, and VM migration between datastores, both the implementations i.e, iSCSI and NFS can be used still there are many aspects on which they differ.

What is NFS?

NFS or Network File System is a kind of network protocol that allows the user to share files stored on a disk with other computers in the network. It was developed by SUN microsystems in 1984. It operates at the application layer of the Open Systems Interconnect (OSI) model. It shares data on the file level. While storing VM templates and ISO images for installing operating systems on virtual machines, NFS data stores are quite a good option and very convenient.

It has 2 versions available:

• NFS Version 2: It was the first version of the NFS protocol that is widely used. It is available on large numbers of platforms. The version of Solaris before 2.5 supports NFS version 2 only.
• NFS Version 3: With the release of Solaris 2.5, this new feature arises. There were several changes in terms of interoperability and performance. It can be run on both i.e, NFS servers and clients.

Key Features of NFS

• Security: It has a kerberized file system interface, which provides privacy and further supports other Kerberos options. In short, it can be secured with firewalls and Kerberos.
• Accessibility: Users can use the protocol across the firewall easily.
• Compatibility: It supports RPC Ports. It can transfer files between computers running Windows and other non-Windows operating systems like Linux or UNIX.
• Scalability: Remote Procedural Call or RPC is available which helps for better support and high scalability. 

Advantages of NFS

• File Support: It has large file support. Also, it has NFS ACL support.
• Usability: It is quite easy to use and provides access to remote files.

Disadvantages of NFS

• Not Secure: It has various dependencies and RPCs, so it is quite insecure in that case.
• Performance: Some versions of NFS tends to slow down during heavy traffic network.

How NFS Works?

NFS is a distributed file system protocol that permits users to get access to documents over a network as if they had been positioned on their local machines. Operating on a purchaser-server architecture, it enables the sharing of directories and documents among systems, making documents seem as part of the user's filesystem. Clients use the mount command to connect and engage with the server-hosted directories, taking into consideration seamless file operations like reading, writing, and modifying. NFS normally utilizes the Remote Procedure Call (RPC) protocol over TCP/IP, making sure compatibility with various network environments, and supports authentication strategies to stable file access.

What is iSCSI?

iSCSI or Internet Small Computer Interface is a kind of network protocol that ensures the user the interaction of initiators and targets for sharing of data in the network. It can both be hardware and software-based. It was developed in 2003 but the first draft of the iSCSI standard was presented to the Internet Engineering Task Force (IETF) in 2000 by IBM. In iSCSI, data is shared on the block level. Basically, it is a transport layer protocol that should be transported over a TCP/IP network.

Key Features of iSCSI

• Protocol: It uses TCP/IP Protocol which enables long-distance IP routing without the requirement of any external gateway hardware.
• Security: It is used for securing IP traffic which is why it helps to establish and manage connections between the host and storage over IP.
• Performance: It has a large storage array. And, as it uses Block storage it is written fast and more efficiently than the other file transfer protocols.
• Cost: It does not require expensive components as it uses Standard Ethernet.

Advantages of iSCSI

• Connections: It supports multiple connections.
• Communication: It aims to communicate the stream between the client and the server.
• Standards: It is built on stable and familiar standards.

Disadvantages of iSCSI

• Latency: It has high latency.
• Vulnerability: It is susceptible to packet sniffing.

How iSCSI Works?

ISCSI is a protocol that permits block-level access to storage devices over a TCP/IP network. By encapsulating SCSI commands into IP packets, iSCSI allows remote systems to seem as they are directly attached to the customer system, facilitating high performance information transfers. The protocol operates the use of an initiator (client) and target (storage server) version, in which the initiator sends SCSI commands to the target for statistics processing. ISCSI helps various authentication strategies and can leverage current infrastructure, making it a cost-effective solution for accessing and managing storage in data centers and business environments. Additionally, it helps multipathing for better redundancy and overall performance.

Difference between NFS and iSCSI

Which one to use between iSCSI and NFS, and why?

Though both iSCSI and NFS have their own features, pros, and cons, still the better option is to choose NFS over iSCSI. NFS works in an efficient manner, with all files whether it is small, medium, or large. Though iSCSI permits applications running on a single client machine to share remote data, it is not directly suitable for sharing data across machines. NFS is always the better choice in all categories. Depending on the user's requirement, one can select which one to choose between them.