Data wiping, also known as disk wiping or secure data destruction, is the process of overwriting the data stored on a hard drive multiple times with meaningless gibberish before disposing of the drive. This is done to permanently destroy any sensitive or confidential data stored on the drive and prevent it from being recovered by unauthorized parties.
Wiping a hard drive is crucial when getting rid of an old computer or external hard drive. Simply deleting files or reformatting a drive does not actually remove the data – it only removes pointers to the data. The original data still remains on the drive and could potentially be recovered. Wiping overwrites the actual data, making recovery virtually impossible.
Companies and individuals should always wipe drives before disposing of them or sending them off for recycling. Otherwise, confidential information like customer records, financial data, or personal information could fall into the wrong hands. Proper data wiping protects privacy and prevents data breaches.
Factors That Affect Wiping Time
There are several key factors that determine how long it takes to completely wipe a hard drive:
Drive size/capacity – Larger capacity hard drives take longer to wipe than smaller drives. For example, it may only take a few minutes to wipe a 250GB drive, but several hours to wipe a 4TB drive. This is because there is more data to overwrite on higher capacity drives.
Interface type (SATA, IDE, etc.) – Hard drives connected via faster interfaces like SATA 3 can be wiped faster than older IDE drives. SATA allows for higher data transfer speeds which reduces wiping time.
Wiping method (DoD 5220.22-M, Gutmann method, etc.) – The wiping algorithm used impacts wipe times. The DoD 5220.22-M 3-pass wipe is faster than the more secure 35-pass Gutmann method. More wipe passes means longer completion times.
In addition, other factors like the age and condition of the hard drive can affect wiping speeds. Newer drives in good health can be wiped faster than older, heavily used drives.1
Mechanical Hard Drives
Mechanical hard drives store data on physical platters that spin at high speeds. To wipe a mechanical hard drive, you need to overwrite the data by recording new random data on top of the existing data. This is typically done by using wipe tools that perform multiple overwrite passes.
A single pass overwrite writes random 1s and 0s across the entire hard drive. However, with the right forensic tools, some data remnants may still be recoverable. For a more secure wipe, multiple overwrite passes are required. The Department of Defense recommends a 3-pass overwrite, while standards like HMG Infosec Standard 5 and NIST 800-88 Revision 1 specify 7-pass and 3-pass wipes respectively.
The time required to wipe a mechanical hard drive depends on the drive capacity and speed. Generally, to perform a full 3-pass wipe of a 1TB hard drive takes 6-12 hours. A more thorough 7-pass wipe of the same drive can take 24 hours or longer. The wipe time also increases for larger multi-TB hard drives.
Solid State Drives
Solid state drives (SSDs) store data differently than traditional mechanical hard drives, so wiping them works a bit differently too. SSDs don’t have physical platters, read/write heads, or magnetic bits – instead they use NAND flash memory chips to store data electronically. This means data can be wiped and written over very quickly on SSDs compared to mechanical drives.
There are a couple main methods for securely erasing SSDs:
- Using the TRIM command – The SSD controller can be instructed to “trim” or delete any deleted sectors that are no longer in use. This is done automatically in the background on many SSDs, but can also be triggered manually by special utilities.1
- ATA Secure Erase – Issuing the ATA Secure Erase command to an SSD will completely reset it to factory settings by deleting the encryption key. This renders all data unreadable.2
Because of these electronic wiping techniques, securely erasing an SSD often takes just seconds or minutes rather than hours for traditional drives. However, SSDs can have idle spare area that is not accessed during normal use – special tools may be required to wipe these areas as well.
Estimating Wiping Times
The amount of time it takes to wipe a hard drive depends on several factors like the drive type, interface, size, and wipe method. Here are some general estimates for wiping times:
|Mechanical Drive via SATA
|Mechanical Drive via USB
|SSD via SATA
|SSD via USB
These estimates are for a single pass zero wipe. More passes or more advanced wipe algorithms like DoD 5220.22-M can increase wipe times significantly.
For example, a 35-pass Gutmann wipe on a 1 TB mechanical drive via SATA could take over 100 hours to complete.
Secure Erase Tools
There are several software tools available to securely erase hard drives. Some of the most popular options include:
DBAN (Darik’s Boot and Nuke) is a free, open-source data wiping tool that completely erases the contents of hard disks. It can be booted from a CD, DVD, or USB drive and ERASES ALL DATA in a matter of seconds to minutes, depending on the speed and size of the drive. DBAN uses a variety of recognized methods for data sanitization, including Department of Defense 5220.22-M algorithms.
Parted Magic is a Linux-based live CD/USB with a wide range of tools for partitioning, data recovery, erasing data, benchmarking, and more. The “Erase Drive” tool can quickly erase a drive securely with methods including multiple overwrite passes and cryptographic wiping. There is a free version and a paid version with additional tools.
HDDerase is a DOS-based boot disk that securely wipes your hard drive. It allows you to erase any hard disk drive, including ATA, SATA, SCSI, SAS, USB, Firewire, and SSD drives. It uses U.S. Department of Defense 5220.22-M (8-306./E) series and Peter Gutmann’s 35-pass series algorithms.
Comparison of Tools and Methods
While all of these tools can securely erase a hard drive, there are some differences between them. DBAN is quick and effective, but lacks options beyond the basic erase. Parted Magic has a wider toolset beyond just erasing. HDDerase uses more advanced wipe algorithms, but runs from DOS which may be less user-friendly. The effectiveness also depends on the algorithm chosen – more passes provides more security but takes much longer to complete.
Verifying the Wipe
Verifying that a hard drive has been completely wiped is an essential step after performing a secure erase. Without verification, you cannot be certain that all data has been removed. Some programs that wipe drives, like software-based secure erase tools, can occasionally fail or encounter errors midway through the process. Verifying a successful wipe ensures no recoverable data remains.
For mechanical hard disk drives (HDDs), you can use a hex editor like Winhex to view raw data from the drive and confirm only null characters (0x00) exist. Checking random physical sectors on the HDD platters is the most thorough verification method. However, opening the drive enclosure and accessing the platters directly will void any warranty.
For solid state drives (SSDs), tools like hdparm can issue a secure erase command to reset all NAND flash cells to their factory state. You can then use hdparm to read the drive and verify that no previous user data responds. SSDs also contain spare area and over-provisioning that require secure ATA commands to sanitize, so only use manufacturer-approved methods.
Ultimately, there is no foolproof way to guarantee 100% irrecoverable data destruction short of complete physical destruction. But following industry-standard wipe verification methods provides reasonable assurance that no usable data remains.
Disposing of the Drive
Once a hard drive has been wiped, you’ll need to properly dispose of it. There are a few options for disposing of hard drives:
Physical destruction is the most secure method of disposal. This involves physically damaging the platters and components inside the hard drive to make the data unrecoverable. Methods like drills, hammers, and shredders can be used for physical destruction (Source).
Donating or recycling hard drives is an environmentally-friendly option, but less secure. Donating to schools or non-profits allows components to be reused. Recycling recovers raw materials. However, there is a risk drives may not be wiped before donation/recycling. Use reputable e-waste recyclers who provide hard drive destruction services (Source).
To conclude, completely wiping a hard drive can take anywhere from several minutes to several hours, depending on the drive technology, size, and the tools used. Mechanical hard drives with spinning disks generally take longer to wipe than SSDs, and using software tools for secure erasing is faster than overwriting data manually.
While there are some general guidelines for estimating wipe times, the exact duration will vary based on the specific drive and method used. The key is to use a secure, verified wiping technique and ensure the drive is fully wiped before disposal. With the right tools and understanding of the factors involved, you can feel confident your drive is truly wiped clean.
NIST – Guidelines for Media Sanitization:
Jon Lasser – Comparison of Disk Wipe Utilities:
C. Wright, D. Kleiman, and S. Sundhar – Overwriting Hard Drive Data: The Great Wiping Controversy:
Bruce Schneier – ATA Secure Erase:
Blancco – Best Practices for Data Destruction: