Unrecoverable data purge?

  • I've got an application that collects sensitive data, with a SQL backend. Due to some recent developments, an order has come down from regulatory bodies that certain parts of the collected data must be destroyed. We'll need to update some tables, over writing some columns with null values.

    What do you think is reasonable to ensure the previous values are not recoverable?

    How far do we take this? Do we deal with Transaction logs, SQL Server logs, backups + tapes, bouncing servers to ensure nothing is in memory, wiping hard drives, etc?

    I've never been asked to destroy data and make sure it not recoverable. Any input would be appreciated.

  • writing NULLs won't do it... you'd have to fill up each column with different data and even that won't insure that bits and pieces of the original data won't remain in places on the disk because of page splits, rebuilding indexes or transaction log allocations and so forth.

    I would think encryption of the sensitive data would be a more controllable methodology.

    The probability of survival is inversely proportional to the angle of arrival.

  • Have a look at this thread where the complexities of 'unrecoverable deletes' was discussed.

    http://www.sqlservercentral.com/Forums/Topic857162-391-1.aspx

    Gail Shaw
    Microsoft Certified Master: SQL Server, MVP, M.Sc (Comp Sci)
    SQL In The Wild: Discussions on DB performance with occasional diversions into recoverability

    We walk in the dark places no others will enter
    We stand on the bridge and no one may pass

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