“Everything is a file” or, more precisely, “Everything is a file descriptor”: this statement alone shows the importance of the storage stack under Linux.

To ensure that data can be accessed reliably and efficiently regardless of the selected file system and the actual physical storage location, numerous layers in the Linux kernel interlock seamlessly: Virtual File System (VFS), page cache, block layer with different I/O schedulers, so-called “stackable devices” such as device mappers and drivers are the most important components involved.

Using the “Linux Storage Stack Diagram”, Werner explains this architecture clearly with the help of several concrete examples. He explains the different areas of the VFS (block-based, network, stackable, pseudo and special purpose file systems) and also goes into detail about the functionality and application areas of various file systems such as ext4 or btrfs. Werner then shows how the resulting BIOs (block I/Os) are processed by the block layer and I/O schedulers (and optionally via stacked devices) before they finally reach the device drivers and physical storage devices.

Join this talk and understand how storage works in Linux :-)