SSDs maintain a layer of indirection between the logical block addresses that computer systems use to access data and the raw flash addresses that identify physical storage. magnetic disks) and the algorithms they use to manage and access that data. Flash-based solid-state drives (SSDs) differ from hard drives in both the technology they use to store data (flash chips vs. Physical destruction and degaussing are also effective. The ATA and SCSI command sets include secure erase commands that should sanitize an entire disk. Software methods typically involve overwriting all or part of the drive multiple times with patterns specifically designed to obscure any remnant data. These techniques provide effective means of sanitizing hard disk drives (HDDs) either individual files they store or the drive in their entirety.
Reliably removing data from persistent storage is an essential aspect of this management process, and several techniques that reliably delete data from hard disks are available as built-in ATA or SCSI commands, software tools, and government standards. 1 Introduction As users, corporations, and government agencies store more data in digital media, managing that data and access to it becomes increasingly important. Overall, we find that reliable SSD sanitization requires built-in, verifiable sanitize operations. This third conclusion leads us to develop flash translation layer extensions that exploit the details of flash memory s behavior to efficiently support file sanitization. Third, none of the existing hard drive-oriented techniques for individual file sanitization are effective on SSDs. Second, overwriting the entire visible address space of an SSD twice is usually, but not always, sufficient to sanitize the drive. Our results lead to three conclusions: First, built-in commands are effective, but manufacturers sometimes implement them incorrectly.
We empirically evaluate the effectiveness of hard drive-oriented techniques and of the SSDs built-in sanitization commands by extracting raw data from the SSD s flash chips after applying these techniques and commands. While sanitizing entire disks and individual files is well-understood for hard drives, flash-based solid state disks have a very different internal architecture, so it is unclear whether hard drive techniques will work for SSDs as well. Spada, Steven Swanson Department of Computer Science and Engineering, University of California, San Diego Center for Magnetic Recording and Research, University of California, San Diego Abstract Reliably erasing data from storage media (sanitizing the media) is a critical component of secure data management. 1 Reliably Erasing Data From Flash-Based Solid State Drives Michael Wei, Laura M.
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