"Before we describe chunkfs, we should first talk about the problems that led to its creation. Chunkfs was motivated by the growing difficulty of reading and processing all the data necessary to check an entire file system. As the capacity of storage grows, the capacity of the rest of the system to read and check that data is not keeping pace with that growth. As a result, the time to check a "normal" file system grows, rather than staying constant as it would if the memory, bandwidth, seek time, etc. of the system grew in proportion to its storage capacity. These differential rates of growth in hardware - like the differences between RAM capacity, bandwidth, and latency - are part of what keeps systems research interesting.
"To understand the change in time to check and repair a file system, a useful analogy is to compare the growth of my library (yes, some people still own books) with the growth of my ability to read, organize, and find the books in the library. As a child, my books fit all on one shelf. I could find the book I wanted in a matter of seconds and read every single one of my books in a week. As an adult, my books take up several bookshelves (in addition to collecting on any flat surface). I can read many times faster than I could when I was a kid, and organize my books better, but finding a book can take several minutes, and reading them all would take me a year or more. If I was trying to find a twenty dollar bill I left in a book, it would take me several hours to riffle through all the books to find it. Even though I am a better reader now, my library grew faster than my ability to read or search my library. Similarly, computers are faster than ever, but storage capacity grew even faster."
