Introduction to Fast File System
This lesson briefly introduces UNIX's first file system.
When the UNIX operating system was first introduced, the UNIX wizard himself Ken Thompson wrote the first file system. Let’s call that the “old UNIX file system”, and it was really simple. Basically, its data structures looked like this on the disk:
The super block (S) contained information about the entire file system: how big the volume is, how many inodes there are, a pointer to the head of a free list of blocks, and so forth. The inode region of the disk contained all the inodes for the file system. Finally, most of the disk was taken up by data blocks.
The good thing about the old file system was that it was simple, and supported the basic abstractions the file system was trying to deliver: files and the directory hierarchy. This easy-to-use system was a real step forward from the clumsy, record-based storage systems of the past, and the directory hierarchy was a true advance over simpler, one-level hierarchies provided by earlier systems.
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