Quantum is suing Riverbed Technology for patent infringement over a patent it owns on data de-duplication, just months after settling a similar lawsuit.

The suit, filed last month in a northern California court, claims Riverbed infringed on US Patent 5990810, "Method for partitioning a block of data into sub-blocks and for storing and communicating such sub-blocks," which was granted to RockSoft in 1999. RockSoft was acquired by ADIC, which was then acquired by acquired by Quantum in 2006.

Quantum wants an injunction from further infringement, damages and attorney's fees.

The lawsuit echoes a dispute Quantum had earlier this year with Data Domain, a data de-duplication vendor. The companies settled by signing a cross-licensing agreement and Quantum received 390,000 shares of Data Domain stock. The two companies agreed to not pursue additional lawsuits.

Quantum's de-duplication technology uses either in-line or post-processing. The manner in which de-duplication occurs has been a matter of hot debate in the last year. Data Domain uses in-line processing.