EMC on Monday increased its offer to acquire storage vendor Data Domain from US$1.8 billion to $2.1 billion in its latest effort to shove aside original bidder NetApp.

The all-cash offer is "clearly superior" to NetApp's $1.9 billion proposal, which includes stock and cash, EMC CEO Joe Tucci said in a letter to Data Domain's board that EMC publicly released.

Data Domain makes deduplication storage systems, which pinpoint redundant data and help companies save disk space.

NetApp had originally entered an acquisition agreement with Data Domain in late May, but EMC subsequently moved with counteroffers in an effort to squelch the deal.

Citing a number of factors, including a $57 million termination fee Data Domain would likely have to pay NetApp, Data Domain's board of directors has recommended shareholders reject EMC's entreaties.

To that end, EMC's latest bid does not include such a fee and other "deal protections," according to EMC.

EMC is also ready to close the deal within two weeks, which is faster than NetApp, Tucci added.

It remains to be seen what effect the new bid will have on Data Domain's board. A company spokesman declined to comment Monday.

Meanwhile, NetApp is proceeding apace, announcing Monday that it had cleared all necessary U.S. regulatory hurdles to proceed with the acquisition. Data Domain shareholders are scheduled to vote on NetApp's offer on Aug. 14, according to NetApp.

NetApp could not immediately be reached for comment.