Kumofs is a simple and fast distributed key-value store which can use a memcached client library to get, set, delete, or compare-and-swap values. tokyo cabinet serves as a high-performance back-end.

main features of kumofs:
* data is partitioned and replicated over multiple servers;
* performance on single node systems is comparable with memcached;
* read and write performance improve when servers are added;
* servers can be added, restarted, or removed on the fly with no
configuration change;
* automatic rebalancing is supported via a consistency control
algorithm;
* it provides a safe compare-and-swap operation;
* the memcached protocol is supported.
kumofs is used at nico-nico douga, the most popular video sharing service in japan.