In a statement, EMC said that its all-cash proposal, which works out at $30 (£18) per share, is superior to the proposed NetApp transaction because it provides Data Domain stockholders with greater value and certainty.
EMC is interested in buying NetApp for its data protection-focused management team and its complementary storage software technology, particularly the deduplication capabilities.
In the past year, EMC has extended such capabilities, which remove copies of the same documents in order to free up storage space, across all its storage arrays.
"The combination of EMC and Data Domain will strengthen EMC's leadership in the fast-growing and very important next-generation disk-based backup and archive market, and will also result in a business larger than $1bn [£606m] for EMC in 2010," said EMC chief executive Joe Tucci. "Our substantially superior proposal is a win-win for both companies."
The announcement follows EMC's bid for Configuresoft last week, which the firm will integrate with its datacentre management line-up.
Tucci discussed plans at EMC World in May for a major acquisition spree to strengthen EMC's position in the market.
Both EMC and NetApp are vendors in the data management and storage space.
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