SD cards, or secure digital cards, are removable flash memory cards used for storing data in portable devices like cameras, phones, and tablets (https://www.easeus.com/computer-instruction/what-is-sd-card.html). They provide a convenient way to expand the storage capacity of these devices. Common uses of SD cards include storing photos, videos, music, documents, apps, and other files.
When a file is deleted from an SD card, it is no longer visible or accessible through the device’s operating system. However, the actual data is often still present on the card until it gets overwritten by new data. This article will explore what happens to files when they are deleted from an SD card, and whether they can be recovered.
File Deletion Explained
When a file is deleted from a storage device like an SD card, the file itself is not actually removed from the storage media. Instead, the reference to the file’s location on the disk is removed from the file system index (Wikipedia, 2022). This makes the space that the file occupies available to be overwritten by new data. Until that overwritten happens, the deleted file remains on the disk.
Deleting a file does not immediately wipe out the data contained within it. The 1’s and 0’s that make up the file remain intact on the physical storage media. However, with the reference removed from the file system table, the operating system no longer knows how to find that data. This gives the appearance that the file has been deleted, even though it still resides on the disk (Aptosolutions, 2022).
Some examples of file systems that work this way include FAT32, exFAT, and NTFS used on SD cards and other storage media. The actual deletion process simply flags the file system entry as available space rather than actually erasing anything (Wikipedia, 2022). This means deleted files can be recovered until overwritten.
File Recovery
When a file is deleted from an SD card, the actual data is often still present on the card even though it appears deleted. The reference to the data in the file system is removed, but the data itself typically remains until that section of the card is overwritten by new information. This means deleted files can frequently be recovered using data recovery software as long as the original data has not been overwritten (https://www.cleverfiles.com/memory-card-data-recovery.html).
There are many data recovery software options available that can scan an SD card and recover deleted files, even after formatting the card. Programs like Disk Drill and Recuva for Windows or PhotoRec for Linux can restore deleted photos, documents, and other file types. The success rate depends on how long ago the files were deleted and what other data has been written to the card since then. The sooner data recovery is attempted, the higher the chance of recovering the deleted files (https://www.popsci.com/story/diy/recover-deleted-files-sd-card/).
Secure Deletion
One of the most secure ways to permanently delete files from an SD card is to use secure deletion methods like formatting or overwriting the data. Formatting an SD card erases all of the existing data by removing file system structures and marking the space on the card as available for new data. This makes recovering deleted files difficult but not impossible with advanced recovery tools.
A more secure option is to overwrite the data on the card by filling it with meaningless random data, essentially scrubbing over the existing files. Software tools like Eraser allow you to overwrite an SD card multiple times according to military grade deletion standards, making the original data irretrievable. This is equivalent to digitally shredding the contents of the card.
Both formatting and overwriting prevent typical recovery of deleted SD card files. However, be aware that forensic data recovery methods may still be able to reconstruct traces of data unless the card is completely overwritten multiple times. For maximum security, physical destruction is recommended.
Physical Destruction
Physically destroying the SD card is an effective way to ensure deleted files cannot be recovered. When an SD card is smashed, shredded, dissolved in acid, melted, or otherwise destroyed through physical means, the data stored on it is rendered unrecoverable. Methods like degaussing (exposing the card to a strong magnetic field to disrupt the magnetic domains that store data) or disintegration can obliterate the contents beyond any hope of retrieval.
According to experts, grinding up the SD card into small fragments and then incinerating the remains is one of the most secure ways to physically destroy the data. The plastic and silicon substrate that stores the data is broken down to the point where specialized forensic data recovery is impossible. While drills, hammers, and scratching can damage an SD card, more thorough physical destruction is required for irrevocable data loss.
Before physically destroying the SD card, it’s important to be certain there are no files you may need in the future. While physical destruction is permanent, there are software options that allow secure deletion of selected files only. However, if the goal is to permanently destroy all data, rendering the SD card to dust is the most foolproof option.
When Files Are Truly Deleted
Deleted files can remain recoverable for a period of time until certain conditions are met that make them essentially unrecoverable. This occurs when all pointers to the deleted data are removed and the storage space is overwritten with new data.
When a file is first deleted on an SD card, it is not immediately erased from the card. The file system simply marks the space occupied by the deleted file as available for new data. The original data remains intact until it gets overwritten. As long as the original data remains intact, the file can be recovered using data recovery software.
Over time, as new data is written to the SD card, the card’s file system will eventually overwrite the space occupied by deleted files. When a deleted file’s original data clusters are overwritten with new data even just partially, it becomes much more difficult to recover that file. The more the original data gets overwritten, the less recoverable the deleted file becomes.
Once the original data clusters of a deleted file are completely overwritten with new data, that file is generally considered to be permanently deleted and unrecoverable by any standard data recovery software. This is because the original contents no longer exist – the space is taken up with new data from other files. At this point, specialized forensic data recovery procedures would be required, if possible at all, to attempt recovering traces of the deleted data.
In summary, deleted files are essentially gone for good when all pointers to the data clusters of the original file are wiped and that disk space has been completely reused and overwritten with new data. At that point, no trace of the original deleted file remains.
Data Recovery Services
If you are unable to recover deleted files from your SD card on your own, you may want to consider using a professional data recovery service. There are companies that specialize in retrieving lost or deleted data from storage devices like SD cards. Some examples of professional SD card recovery services include:
These services use advanced techniques and tools to attempt recovering lost files. However, professional data recovery can be expensive, with costs ranging from $300 to over $1000 depending on the service and amount of data. There is also no guarantee that the files will be successfully recovered. The process could potentially cause further data loss if not performed properly. So while professional recovery services are an option if DIY attempts fail, weigh the risks and costs before proceeding.
Precautions
Accidentally deleting important files can be a frustrating experience. However, there are some precautions you can take to avoid accidental file deletion:
Enable file versioning in your operating system like Windows 10 [1] or macOS. This will save previous versions of your files, allowing you to restore them if accidentally deleted.
Use cloud backup services like Google Drive or Dropbox to keep copies of your files online. This protects your data if files are deleted from your local storage.
Store files on external drives that you can unplug when not in use. This isolates the data from accidental deletion.
Set file and folder permissions to read-only or restrict delete access for other users.
Enable file recovery software that can scan and recover deleted files from your system.
Use version control systems like Git when working on code projects. This tracks changes and allows restoring previous versions.
Be very careful when deleting files and emptying the Recycle Bin. Always check the contents first to avoid losing data.
Creating backups and restricting permissions are effective ways to avoid the frustration of accidental file deletion.
Summary
In this article, we looked at what happens when you delete files from an SD card.
When you delete files from an SD card, the files are not immediately erased from the storage media. Instead, the space they occupied is simply marked as available to be overwritten by new data. The original file contents remain until that space is reused.
This means deleted files remain accessible until they are overwritten. Specialized recovery software can scan storage media and rebuild deleted files by piecing together the still-present data. However, the longer you use the SD card after deletion, the higher the chance partial overwriting makes files unrecoverable.
There are techniques like secure deletion and physical destruction that more permanently erase files by overwriting their data multiple times or damaging the physical media. But under normal deletion, files remain recoverable for a window of time before being progressively lost as space is reused.
Additional Resources
If you need more information on recovering deleted files, here are some additional resources:
Download Recuva | Recover deleted files, free! – Recuva is a free deleted file recovery tool from the makers of CCleaner that can help recover deleted files.
Deleted Data Recovery Services | Recover Deleted Files & Data | Gillware – Gillware offers professional deleted file and data recovery services if you need help recovering deleted files.
Data recovery forums like Data Recovery Forums allow you to get recommendations on data recovery software and services from other users.
Websites of data recovery software vendors like EaseUS, Stellar, and Kroll Ontrack provide information on their tools and guidance on recovering deleted files.
Subreddits like r/datarecovery on Reddit are communities where you can get data recovery advice and recommendations.