Distributed network block device
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A Distributed Network Block Device (DNBD) is a read-only and caching network block device and supports following main features:
- replication of servers for robustness
- multicast communication and caching of network traffic for scalability
These characteristics make it suitable especially for use in wireless networks, e.g. for diskless clients or to share multimedia files in such an environment. The servers can export a file or block device equipped with an operating system, movies, music, etc. Several clients can import the block device and access it like a local hard disk. However, each block transfer over the network can be cached by all clients: If several users on each client start to watch a movie within a certain time interval, the movie data has to be transmitted only once (depending on the cache size). The network is not burdened with unnecessary traffic.
DNBD can be used together with cowloop [1] or unionfs [2] in order to get local write semantics, e.g. for diskless clients. Especially in wireless environments with limited bandwidth, caching can increase boot-up time enormously.