The 17GB file occupies 325MB of storage space.
The 17GB file occupies 325MB of storage space.
I wanted to give Dreadnought a try, so I installed it. It didn’t suit me. When I was clearing out storage space on my 500GB hard drive for a new game, I checked the details and noticed: Size: 17.1GB Size on disk: 325MB. If my knowledge about how this works is right (HDDs are divided into clusters, and if each cluster is 512 bytes, a file of 20 bytes would occupy 512 bytes), then this shouldn’t be happening. How much actual space does it use on my drive?
They're referred to as sparse files. An app can inform the operating system it intends to store 17 GB on disk, prompting the OS to identify the biggest uninterrupted areas of free space and reserve them without actually writing anything there. As data flows into those empty sections, the OS breaks them down further if necessary. If another program requests space, the OS may reclaim one of those reserved blocks and transfer the reservation to the other application. It's a complex process but you can find more details on sparse files and NTFS compression here: https://en.wikipedia.org/wiki/Sparse_file and here: https://blogs.msdn.microsoft.com/ntdebug...mpression/. And yes, the NTFS file system stores certain file information in hidden areas within each partition (files). Typically, each new file consumes at least 512 bytes to store its metadata—such as name, folder location, permissions, and user rights. If a file is smaller than roughly 100–150 bytes, the entire content can be kept in that internal space instead of using external storage. In this scenario, once more bytes are needed, the OS locates an empty chunk, moves the necessary data there, writes the rest, and updates the metadata to maintain consistency.