# Hanoi Key/Value Storage Engine This Erlang-based storage engine implements a structure somewhat like LSM-trees (Log-Structured Merge Trees, see docs/10.1.1.44.2782.pdf). The notes below describe how this storage engine work; I have not done extensive studies as how it differs from other storage mechanisms, but a brief brows through available online resources on LSM-trees indicates that this storage engine is quite different in several respects. The storage engine can function as an alternative backend for Basho's Riak/KV. Here's the bullet list: - Insert, Delete and Read all have worst case log2(N) complexity. - The cost of evicting stale key/values is amortized into insertion, so you don't need to schedule merge to happen at off-peak hours. - Operations-friendly "append-only" storage (allows you to backup live system, and crash-recovery is very fast) - Supports range queries (and thus eventually Riak 2i.) - Doesn't need much RAM, but does need a lot of file descriptors - All around 3000 lines of pure Erlang code ### Deploying the hanoi for testing with Riak/KV You can deploy `hanoi` into a Riak devrel cluster using the `enable-hanoi` script. Clone the `riak` repo, change your working directory to it, and then execute the `enable-hanoi` script. It adds `hanoi` as a dependency, runs `make all devrel`, and then modifies the configuration settings of the resulting dev nodes to use the hanoi storage backend. 1. `git clone git://github.com/basho/riak.git` 1. `cd riak/deps` 1. `git clone git://github.com/basho/hanoi.git` 1. `cd ..` 1. `./deps/hanoi/enable-hanoi` # which does `make all devrel`