Disk and File Caches

To that end, there are several types of cache used in a computing environment, two of which will be discussed here. The first type would be the disk cache, which is used to reduce the read/write time from/to a hard disk drive because it is used to store data that is likely to be used repeatedly or will be needed soon. This is where "temporary" files are stored until it is needed again (whenever that might be). Incidentally this also leads to some technical solutions calling for clearing of the "disk cache". Whereas the file cache, A.K.A. virtual memory, is what an operating system uses in case of running out of physical memory (RAM). It is very easy to get both caches confused, as both resides physically on the hard drive when deployed, and both are used as "scratch space" by either the operating system or an application, or both.

For example, Microsoft Windows allows one to set the file cache option, which sets aside an amount of space to be used for virtual memory. But in Adobe Photoshop, the user can define "scratch disks" to be used during an image operation (essentially a disk cache). There are a lot of similarities between the two, but there is one clear distinction. A disk cache allows for temporary files to be created (and manipulated manually), which increases or decreases with use. But a file cache usually is a block of hard drive space that is reserved, and cannot be used by anything else.

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