http://stackoverflow.com/questions/2252163/how-does-voldemort-compare-to-cassandra
http://www.project-voldemort.com/voldemort/
Both are fast (> 10k ops/s per machine). Because of their storage designs, I would expect Cassandra to be faster at writes, and Voldemort to be faster at reads. I would also expect Cassandra's performance to degrade less as the amount of data per node increases. And of course if you need more than just a key/value data model Cassandra's ColumnFamily model wins.
- Regarding write speed, Cassandra should be faster -- it is designed to be faster to write than read (you can avoid immediate disk hit for writes due to specialized way storage is done)
But main difference I think is actually not performance but feature set: Voldemort is strictly a key/value store (currently anyway), whereas Cassandra can offer range queries (with order-preserving partitioner), and bit more structure around data (column families etc). Former is an important consideration for design; latter IMO less so, you can always structure BLOB data on client side.
- Data is automatically replicated over multiple servers.
- Data is automatically partitioned so each server contains only a subset of the total data
- Provides tunable consistency (strict quorum or eventual consistency)
- Server failure is handled transparently
- Pluggable Storage Engines -- BDB-JE, MySQL, Read-Only
- Pluggable serialization -- Protocol Buffers, Thrift, Avro and Java Serialization
- Data items are versioned to maximize data integrity in failure scenarios without compromising availability of the system
- Each node is independent of other nodes with no central point of failure or coordination