Reliably Erasing Data From Flash-Based Solid State Drives
Michael Wei, Laura M. Grupp, Frederick E. 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
Reliably erasing data from storage media (sanitizing the
media) is a critical component of secure data management.
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.
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. Our results lead to three conclusions:
First, built-in commands are effective, but manufacturers
sometimes implement them incorrectly. Second,
overwriting the entire visible address space of an SSD
twice is usually, but not always, sufficient to sanitize the
drive. Third, none of the existing hard drive-oriented
techniques for individual file sanitization are effective on
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.
Overall, we find that reliable SSD sanitization requires
built-in, verifiable sanitize operations.