One terabyte of data is roughly the equivalent of millions of books, and that is the amount of Clinton administration records - including sensitive national security information - contained on a hard drive that has gone missing from the National Archives, according to a Republican lawmaker.

Rep. Darrel Issa, R-Calif., says he is asking the National Archives and Records Administration Acting Director Adrienne Thomas to appear on Thursday before the House Oversight and Government Reform Committee to answer questions about the missing hard drive.

    Issa, the committee's ranking Republican, issued a news release in which he said that the NARA Inspector General's Office briefed committee staff today on an ongoing investigation into the loss of the device from NARA's storage facility in College Park, Md., sometime between October 2008 and March 2009.

    "The IG is investigating the situation as a crime," assisted by the Secret Service and Department of Justice, the news release said.

    The one terabyte of data on the hard drive, it said, includes the Social Security numbers of more than 100,000 people, including the daughter of former Vice President Al Gore, contact information for various former Clinton administration officials, Secret Service and White House operating procedures, event logs, the logs of social gatherings, political records and other sensitive information.

   "This egregious breach raises signficant questions regarding the effectiveness of the security protocols that are in place at the National Archives and Records Administration," Issa was quoted as saying.

    The hard drive, it seems, was removed from a "security" area and taken to a workspace accessible by  at least 100 "badge-holders," the news release said, quoting the NARA IG staff.