Self-securing storage prevents intruders from undetectably tampering with or permanently deleting stored data. To accomplish this, self-securing storage devices internally audit all requests and keep old versions of data for a window of time, regardless of the commands received from potentially compromised host operating systems. Within the window, system administrators have this valuable information for intrusion diagnosis and recovery. Our implementation, called S4, combines log-structuring with journal-based metadata to minimize the performance costs of comprehensive versioning. Experiments show that self-securing storage devices can deliver performance that is comparable with conventional storage systems. In addition, analyses indicate that several weeks worth of all versions can reasonably be kept on state-of-the-art disks, especially when differencing and compression technologies are employed.