EMC Monday offered to purchase data-storage developer Data Domain for $1.8 billion in cash, surpassing its rival NetApp's previous offer of $1.5 billion in stock and cash. Data Domain has yet to accept either offer.

The Santa Clara, Calif.-based Data Domain makes deduplication storage systems. At the time of its offer, the Sunnyvale, Calif.-based NetApp said that Data Domain's portfolio would expand its reach in the market for heterogeneous disk-based backup.

NetApp said it intends to operate Data Domain as a product line within its product operations organization. Also, the Data Domain sales organization would be integrated with NetApp's sales force.

The Hopkinton, Mass.-based EMC said its all-cash proposal is not subject to a financing or due diligence contingency. EMC said it will use existing cash balances to finance the transaction.

EMC warned Data Domain that because its offer is identical to the offer of NetApp in all aspects other than the increase in price, Data Domain's board of directors would risk breaching its fiduciary duties to its shareholders.

In order to speed acceptance of their offer, EMC said it is waiving its right to review Data Domain financial data; in addition, the firm stated that Data Domain does not need to enter into discussions or negotiations with EMC or sign any confidentiality agreements with it.