Erase Method

Overwrite erase method(HDD、SSD、eMMC)

Erase method	Iteration	Written/Verify pattern
Random numbers 1 time	1	random numbers 1 time
Random numbers 2-5 times	2～5	random numbers 2-5 times
random numbers 6-9 times	6～9	random numbers 6-9 times
NSA recommendation	3	random numbers 2 times → zero
US Army compliant (AR380-19)	3	random numbers → fixed value 1 → fixed value 2
US Navy compliant (NAVSO P-5239-26)	3	fixed value 1 → … → fixed value 3 → verify
US Air Force compliant (AFSSI5020, AFI33-202)	7	fixed value 1 → … → fixed value 7 → verify
US Department of Defense complaint (DoD5220.22-M)	3	fixed value 1 → fixed value 2 → random numbers → verify
US Department of Defense complaint (DoD5220.22-M ECE)	7	fixed value 1 → fixed value 2 → random numbers 2 times → fixed value 1 → fixed value 2 → random numbers → verify
NCSCcomplaint (NCSC-TG-025)	3	fixed value 1 → … → fixed value 3
NCSC compliant 2 times (NCSC-TG-025)	6	fixed value 1 → … → fixed value 6
Gutmann recommendation	35	random numbers 4 times →fixed value 1 → … → fixed value 27 → random numbers 4 times
Zero write method ＋verify	1	zero → verify

"Erasure verify" is the process of checking whether a value has been written correctly after a write operation.
NSA : The National Security Agency
NCSC: The National Computer Security Center
"Gutmann recommendation" is an erasure method proposed by Gutmann in his paper published in 1996, which analyzes data encoding methods (formatting methods) on magnetic media such as RLL (Run Length Limited) and MFM (Modified FM), Theoretically, the overwritten data that leaves the fewest traces of data is calculated.
"Zero write method＋verify" is an erasure method described in SP800-88 Rev. 1, published by the National Institute of Standards and Technology (NIST) in 2014. It complies with the "Clear" level erasure method, which is resistant to attacks using commonly available tools.

Erase method	Written/Verify pattern
Secure Erase +verify	Secure erase command for target disk →verify

Secure erase is an erase function provided by disks (HDD, SSD, eMMC). By sending a Secure Erase command to a disk, the erasure process is executed only by the disk's internal processes, completely erasing data. Disk Shredder sends the Enhanced Security Erase Unit (or Security Erase Unit if not supported) command to disks with Serial ATA or IDE connections, the Format NVM command to NVMe-connected SSDs, and the eMMC Secure Erase command.
For models with SSD and eMMC, "Secure Erase + verify" is automatically selected. If you wish to select another erase method, please specify it at the time of execution.
Although it is possible to perform overwrite erasure on SSD and eMMC, "DiskShredder ToGo" recommends erasure by secure erasure.
Secure erase is also available for some HDDs. However, secure erasure of HDDs takes a long time, during which time the progress is not displayed and cannot be aborted. Furthermore, please note that turning off the power to the computer during secure erase may make the HDD inaccessible. For these reasons, please use overwrite erase instead of secure erase for HDDs if there is no particular need to do so.

Erase method	Written/Verify pattern
Sanitized erase +verify	Sanitize command for the target disk →verify

"Sanitized Erase+verify" can be selected for some disks equipped with the sanitize function. By sending a command to the disk to perform sanitized erasure, the erasure process is executed only by the disk's internal processes, completely erasing the data. The level of unrecoverability of the original data is even higher than Secure Erase, and corresponds to the "Purge" level, which is higher than "Clear" in NIST SP 800-88 Rev. 1.
For models equipped with SSD, "Secure Erase + verify" is automatically selected. If you choose "Sanitized Erase + verify", please specify it at runtime.
Sanitized Erase is also possible for some HDDs. However, sanitizing and erasing HDDs takes a long time, during which time the progress is not displayed and cannot be aborted. Furthermore, please note that turning off the power to the computer during sanitization and erasure may result in the HDD becoming inaccessible. For these reasons, please use overwrite erase instead of sanitize erase when there is no particular need for HDD.

Erase method	Written/Verify pattern
HDD: random numbers SSD: Secure Erase+verify	random numbers 1 time Sanitize command for the target disk →verify

For models with HDDs and SSDs, "Random numbers (one-time write)" is selected as standard for HDDs, while "Secure Erase+verify" is selected as standard for SSDs to erase data simultaneously.
If you want to execute different erase methods for HDDs and SSDs, please select the target disk to be erased on the confirmation screen for the target disk and specify the erase method you want to execute.