Historically, data wiping was considered the process of removing data using an overwriting technique, where new patterns of data were written over the original bits, particularly on magnetic media (HDDs). Today, data wiping involves more than simply overwriting the storage media. It covers the secure removal of data using the method best suited to the device type. For example, SSDs should be wiped using native firmware commands, while SEDs may be sanitized using Cryptographic Erase (CE) if the device supports it.
Data wiping is also discussed in the context of Media Sanitization in the NIST 800-88 guidelines. It involves applying a technique or method that makes access to the target data infeasible for the intended level of recovery effort. This includes both logical techniques, such as overwriting or cryptographic erase (CE), and physical techniques, such as degaussing.
Why is Data Wiping Necessary?
The need for ‘Data Wiping’ emerged as organizations recognized that standard deletion methods are often not enough to prevent data recovery from storage media. This is due to ‘Data Remanence’, where residual data may remain on storage media even after files are deleted, or a device is taken out of service without proper sanitization.
What is the History Behind Data Wiping?
Early data wiping practices included clearing and purging storage media by overwriting data with specific patterns multiple times, commonly termed ‘Overwrite Passes’. For example, the U.S. Navy's NAVSO P-5239-26, published in 1993, described procedures for purging hard disks by overwriting addressable locations with specific data patterns and a nonlinear pseudorandom bit sequence, followed by verification. It also noted that defective or remapped areas could remain inaccessible to software using only logical addressing. Here, the standard required destroying the data using 3 overwrite passes:
- Pass 1: Overwriting information with a specified character
- Pass 2: Overwriting with the complement of the specified character on the drive, and
- Pass 3: Overwriting with a random character, followed by Verification
Peter Gutmann's Secure Deletion of Data from Magnetic and Solid-State Memory method later became well known as Peter Gutmann’s 35-pass overwrite method. It used a series of overwrite patterns associated with different magnetic recording and encoding techniques.
NISPOM manual that is popularly known as the US DoD 5220.22-M Standard, specifies a process of overwriting hard disk drives (HDDs) with patterns of ones and zeroes. The standard defines the process of writing the media with 3-overwriting passes, with verification at the end of each Pass.
- Pass 1: Overwrite the media with a single character
- Pass 2: Overwrite the media with the complement of that character
- Pass 3: Overwrite the media with a random character
The effectiveness of host-level overwriting depends on the storage technology and how data is managed by the device. On magnetic HDDs, overwriting addressable storage locations can directly modify the locations being addressed. On SSDs and NVMe drives, mechanisms such as wear leveling, over-provisioning, and reallocation can result in data being stored in physical locations that are not directly accessible through normal host addressing. This change in storage architecture also changed how data wiping is approached.
Is More Than One Pass Necessary for Secure Data Wiping?
For many years, data wiping was discussed in terms of the number of times data should be overwritten. This resulted in different approaches being associated with one, three, seven, thirty-three, or thirty-five passes. However, the need for multiple overwrite passes was rooted in the characteristics of magnetic storage and the recording technologies used by earlier hard drives. As recording technologies changed and storage architecture became more sophisticated, the rationale for treating a higher number of overwrite passes as inherently more secure diminished. A larger number of overwrite passes should therefore not automatically be equated with better or more secure data sanitization.
NIST SP 800-88 introduced the Clear, Purge, and Destroy sanitization categories in its original 2006 release. Clear refers to logical sanitization using standard read/write commands, protecting against simple data recovery. Purge refers to more advanced techniques such as device-level firmware commands like ATA Secure Erase that protect data against laboratory-level recovery attempts. Revision 1, published in December 2014, extended these categories to address newer storage technologies such as SSDs. That same year, the DoD 5220.22-M (NISPOM) Clearing and Sanitization Matrix cited NIST SP 800-88 (2006 publication) as a resource an organization could use to make sanitization decisions based on the sensitivity of their data.
As a result, modern sanitization guidance emphasizes picking a data wiping strategy that is suitable for the storage system and the needed level of assurance rather than a specific number of overwrite passes. NIST SP 800-88 Rev. 2, released in September 2025, suggests referring to appropriate standards, such as IEEE 2883:2022, for technology-specific sanitization approaches rather than imposing a general overwrite-pass requirement.
Therefore, multiple overwrite passes are not required for secure data wiping. Organizations can select between Clear and Purge methods based on device reusability, data sensitivity, and the required assurance level. For some magnetic HDDs, a single overwrite pass may be appropriate for the required sanitization – Clear / Purge. For SSDs and other flash-based media, Purge requires running device-level commands such as ATA/NVMe Secure Erase, Block Erase, or Cryptographic Erase.
What are Some Common Misconceptions About Data Wiping?
Several assumptions about deleting, formatting, and overwriting data can lead to confusion about what constitutes secure data wiping. The following are some common misconceptions about data wiping.
- Does deleting a file wipe the data?
No. Deleting a file generally removes its reference from the file system but does not remove the underlying information from the storage media.
- Does formatting a drive securely wipe its data?
No, formatting is an insecure method for wiping data. Formatting primarily prepares or restructures the storage for use and should not automatically be treated as a secure data-sanitization method.
- Does using more overwrite passes for data wiping ensure security?
No. Choosing multiple passes like Peter Gutmann – 35 passes or repeating an unsuitable sanitization technique does not necessarily ensure data security. The method chosen for data wiping must be appropriate for the storage technology on which erasure is performed.
- Is overwriting suitable for every storage device?
No. Overwriting can be appropriate for some storage media like HDDs, but storage architecture and device capabilities must be considered when selecting a sanitization method. Example: On some SMR drives (Shingled Magnetic Recording), overwriting would fail despite being a magnetic hard drive.
Final Thoughts
Data wiping should not be viewed as a single technique or a fixed number of overwrite passes. The term has evolved alongside the storage technologies to which it is applied, and what constitutes an appropriate wiping approach depends on how the device stores and manages data.
For organizations, the key takeaway is to look beyond the term “Data Wiping” and evaluate the actual sanitization method being used, the storage technology it is designed for, and the level of assurance it provides. This helps avoid treating file deletion, formatting, or a higher overwrite count as equivalent to secure data sanitization.
