This means even modifying an existing file will typically write the file in other cells than their previous location, and mark the previous location as now available for new use.Įven on HDDs, SMART can remap clusters silently if they start to fail.
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SSDs spread the wear by writing blocks to least used slots. Shredding individual files doesn't actually work against advanced file recovery methods. While it's not guaranteed the most accurate way to tell what's still there, you can always run one or more file recovery apps to see what deleted files & file fragments still remain. wherever they write files they overwrite any data that was stored there previously - wherever they leave any disk free space, old data may remain. Now, to your initial question about rest/refresh tools. Actually reading any data left over that way requires an expensive specialized lab service, but nonetheless, most erasing apps give you options to run multiple passes, to better ensure that nothing gets left behind. When you overwrite part or all of the disk that means that there might be old data left on those fringes, especially if say the data was written to the right & the head was to the left when it overwrote that data. There's a little bit of wiggle room where a head might write a track a little to the right or left instead of dead center. When you write to a regular hard drive the write heads float above the spinning platters on a cushion of air. That said, it may not be possible to completely erase all of the data stored on flash RAM, & some drives have a special command or feature to delete everything, but how well that works can vary. Since having to clear a space before you can write to it would make SSDs slower, they use Trim processes that automatically clear the storage space formerly used by now deleted files *before* you need to write fresh data there. On a regular hard drive overwriting storage space both deletes the old data & writes new - with an SSD that same thing takes two separate operations. Because the last piece of a file may not fill up the small section of the drive where it's stored, the space that's not used can contain old data from a previous file - some erasing apps can oversrite those small spaces too. Overwriting every bit of disk space clears that data, but it takes a long time, so most erasing apps just overwrite the parts of the disk where a file or files are stored, though some also have the option to overwrite free space. That's why all of those deleted file finding or recovery apps work.
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When you delete a file the only thing that goes away is the TOC entry - the pieces of the file are still there until something else is written in their physical space. The files themselves are stored in small pieces on the drive partition, and this sort of TOC records where the pieces of each file are physically on the drive.
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When you look at the files/folders in Windows Explorer what you're seeing is more-or-less the Table Of Contents for that drive partition.
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The suite also handles file deletion with random overwriting, so if you already have it installed you don't need to install another tool to carry out shredding. CCleaner (opens in new tab) is one of the best tools for checking what files are taking up valuable space on your PC.