IBM has bought de-duplication specialist, Diligent Technologies, IBM's third strorage buy in just a few months.

Diligent is known for its de-duplication technology, a technique for saving storage space by eliminating redundant data, such as multiple copies of the same e-mail attachment within an e-mail archive. The company's ProtecTIER product employs an in-line de-duplication engine that does the work as data is brought into a system, not after the fact, which saves time, according to Diligent.

Diligent's technologies and its workers will be brought under IBM's system storage business unit within the systems and technology group.

One observer questioned whether the Diligent deal could hurt players such as Hitachi Data Systems, given that it has been reselling ProtecTIER.

"Now that the IBM acquisition of Diligent Technology appears to be all but a done deal, where does that leave HDS and their customers, as HDS is now left without a viable de-duplication technology in one of the hottest sectors in data storage?" wrote Jerome Wendt, president of DCIG, a consulting firm, on his blog.

The buy marks the third storage-related grab by IBM in just the past few months, following its moves to acquire XIV and FilesX.

De-duplication is seen as a hot trend within the storage space. The 451 Group last year predicted the market sector could grow to US$1 billion by 2009. The space includes a range of independents such as ExaGrid, along with major vendors like Symantec.

Oracle also features the capability in its flagship 11g database, and Sun Microsystems recently made a de-duplication announcement as well.