Data Domain said Wednesday it has signed a definitive merger agreement with EMC and terminated its previously announced merger deal with NetApp. Data Domain said it paid NetApp a $57 million termination fee under terms of that agreement.

EMC launched a tender offer for Data Domain, a vendor of de-duplication storage systems, on June 2. Data Domain said its board considers the terms to be in the best interests of its shareholders and recommends they tender their shares to EMC.

EMC's offer is set to expire July 17, but EMC can extend the offer period if it needs to.

In a statement Wednesday, NetApp Chairman and CEO Dan Warmenhoven said his company was focused on creating long-term value for its shareholders.

"We therefore cannot justify engaging in an increasingly expensive and dilutive bidding war that would diminish the deal’s strategic and financial benefits,” Warmenhoven said. NetApp said it had received the $57 million termination fee.

The bidding war for an acquisition that will total about $2.1 billion highlighted the intense interest in data de-duplication, which identifies redundant data and deletes it in order to save storage space. As the amount of data enterprises need to store rapidly grows, they are looking for ways to reduce how much storage they have to buy. De-duplication can slash the space requirement for many types of data by more than half, vendors say. Data Domain was a pioneer of this technology, which most storage vendors have in some form today.

Data Domain agreed to a $1.5 billion bid from NetApp on May 20, but EMC countered that with an unsolicited offer of $1.8 billion. NetApp soon surpassed that, but on Tuesday EMC brought out its offer of $33.50 per share, or $2.1 billion. EMC Chairman, President and CEO Joe Tucci has said his company made a more attractive suitor because, among other things, it was offering all cash instead of NetApp's combination of cash and stock.

EMC is the biggest vendor primarily focused on storage, with annual revenue of more than $14.5 billion.