Terminology

What is the difference between network block devices and network file systems?

Before we speak about the hows and whys, let’s talk about the terms we are going to be using. There is some confusion to be had, if you are not familiar with it. So, let’s get started.

Small note: The term “disk” in this article refers to HDD as well as SSD.

Block Device

A block device, is, by definition, a device that stores or reads data in blocks. This means, always a certain amount of data is transmitted at every operation. How big that block is, highly depends on the protocol used.

File System

A file system is how your hard disk is formatted. It manages how the data is physically laid out, how the journal (the database of where which file is on the disk) looks like, which security features it supports or how big the files can be. For example, NTFS supports bitlocker, an encryption method, or security descriptors that tell Windows who can access files. FAT32 from Windows98 only supports files up to 4 GiB, NTFS supports very large files.

Network File System

Now comes the confusing part. I said previously, that file system means how your disk is formatted. This ain’t true for Network File Systems. They don’t care which file system your disk is formatted as. There may be some that do care, but most common used Network File Systems don’t. As long as the OS can handle it, they can use it.

A network file system is for example SMB, ...