This Linux filesystem was supposed to change everything—here’s the dark reason it failed
There are dozens of Linux file systems and I’m sure you’ve heard of ReiserFS at least once. He promised a lot, but ultimately failed. I could give you a technical reason for its disappearance, but that would be dishonest. The real reason is much darker, and if you heard it, you might appreciate your day a little more.
ReiserFS was a very promising project in the early days of Linux, and its lead developer, Hans Reiser, had high aspirations for his invention and his company (Namesys). ReiserFS took its Linux file system in a whole new direction with its B-tree indexing and tail-packing features, something sorely needed at the time. With distributions like SUSE adopting it early, the future looked bright for Hans Reiser’s gem, but fate had other plans.
Problems that need to be solved
Inefficient searches and storage have bogged down Linux
In the early days of Linux, file systems weren’t as good as they are today: scalability was an afterthought, and Ext2 is a great example.
In Linux everything is a file and directories are no different. What you see as a folder icon is just an illusion, and the directory is actually a special file that stores directory data. The reality is slightly more complex, involving an inode, but that’s the general idea.
To search for a particular file name in a directory, Ext2 performed a linear search through its directory file, meaning it checked each file entry one after the other. When a directory contains millions of files (like a mail server) and requests come in quickly and quickly, the server begins to buckle under the enormous pressure.
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B-tree indexing
A fast, scalable solution capable of handling millions of files
A B-tree is a self-balancing data structure organized like a Christmas tree. To avoid all the gory details, the main advantage of ReiserFS is its incredible speed. For example, searching for a tree with billions of articles takes only a few dozen operations. For ReiserFS, storing metadata in the tree meant that there was no limit to the number of files a directory could contain, unlike Ext2, which bogged down with each file added.
ReiserFS also stored everything in the tree: metadata and file data. This was very different for its time and eliminated performance bottlenecks during metadata operations.
Tail wrapping
A judicious and space-saving technique
ReiserFS saved space by grouping small files into the same block, which is a small limit (e.g. 4 KB) that most file systems use to allocate standard space. When you save a 6 KB file, it allocates two 4 KB blocks, of which half a block remains unused. ReiserFS crammed small files into the unused tail of the block, reducing the number of allocations and wasted space. Such a technique is useful for servers that host many small files, which at the time were all web, mail, and file servers.
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From the main line to the marshalling yard
An unrecoverable error
This looked good for Hans and his team, and in 2001, ReiserFS found its place in the core mainline. This lasted for several years until Hans and his company encountered a problem. tiny problem: he murdered his wife.
In 2008, the State of California convicted Hans of first degree murder. He initially denied it at his trial, but later confessed on tape to get a reduced sentence of second-degree murder, punishable by 15 years to life in prison. Hans described punching his wife in the mouth and then strangling her while his children played computer games in another part of the house. He kept her body in the bathroom and then in his car for two days while he looked for a place to bury her.
According to Hans, his wife (a doctor) was an “unfathomable” psychopath and a gifted liar who was “jealous of her own children.” He also later claimed in a 2012 civil trial that he was protecting them because she had Munchausen by proxy — a mental disorder in which a caregiver manufactures or induces an illness in a person in their care. At the same trial, he compared himself to Moses, who murdered a slave master and buried the body in the sand.
Around the time of the first trial, his business had become inactive and ceased all operations. Hans was effectively bankrupt, and in the civil trial he was ordered to pay $60 million in damages to his children.
The inevitable demise of ReiserFS
It’s not us, it’s you
To add to the woes, cracks began to appear in ReiserFS, ranging from subtle file corruption issues to the use of outdated kernel APIs. The most pressing issue was that ReiserFS was involved in the Y2038 issue. Although ReiserFS can represent times up to 2106, it did not modernize with the kernel, and in 2022 it was deprecated in the kernel mainline, then removed in 2024.
Hans had big plans for ReiserFS, and for a time his company delivered on them. Things were getting better for him, but like the rest of us, he couldn’t escape real life. Hans clearly had problems and wasn’t solving them. It cost him his freedom, his children and his dream.
The moral of the story is: if you don’t keep your code, Linus will remove it from the mainline.
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