With Solid State Drives taking over, the term "disk" is becoming a misnomer. What word do you use? "File system", "persistent storage" and "mass storage" are correct, but a little long. Is there anything better?


I should add that I am writing software documentation, which in retrospect was a serious omission.

If you were explaining how to disassemble a computer, you would never say, "remove the file system". Here, "hard drive" would be the correct universal term.

In software, the two main places to read and write data are disk and memory (or should I say core?). I ended up using "file system" in my document.

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    I mostly like this answer, but I would clarify something: the three terms you've cited are wrong for the reasons given. In fact, Mass Storage and File System are very wrong. If you want to go esoteric, you could say "block device". I would note, though, that I've never been bothered by anyone calling SSDs "disks", although "Solid State Hard Disk Drive" would probably be taking it too far, since we tend to contrast SSD vs HDD.
    – sirosen
    Commented Aug 12, 2015 at 0:36
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    You haven't dialed your mom on your iphone yet? Commented Aug 12, 2015 at 4:14
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    What's wrong with "Solid State Drive" (or SSD) ?
    – msam
    Commented Aug 12, 2015 at 17:13
  • I was amused that, in the recent Man from U.N.C.L.E. movie, they repeatedly referred to the storage medium for some secret bomb design as a "disk", even though, at that time, a "disk" was at least a foot in diameter and weighted a minimum of 100 pounds, and the item they handled (perhaps 5 inches across and 2 inches thick) appeared to be a tape cartridge (which in a later scene they pried open in order to burn what was obviously a tape within).
    – Hot Licks
    Commented Aug 22, 2015 at 18:48

7 Answers 7


A very generic term would be storage media, which I remember being used to describe all sorts of data storage devices from over 25 years ago. However, it applies to CDs and DVDs (both of which are actual disks) and other removable media in addition to less mobile versions such as internal drives and network attached storage.1

If you want a term specific to what a typical standalone digital device would use, you can refer to its internal storage 2, or perhaps more succinctly storage.3

  1. Forensicon
  2. PC.net
  3. Wikipedia

Your addendum has changed the nature of the question. You are not looking for a term to describe the physical device from which the data is written and read. Instead, you want a term to describe the service an operating system provides to store and retrieve files. The file system (also filesystem) is that service.

Without a file system, information placed in a storage area would be one large body of data with no way to tell where one piece of information stops and the next begins. By separating the data into individual pieces, and giving each piece a name, the information is easily separated and identified. Taking its name from the way paper-based information systems are named, each group of data is called a "file". The structure and logic rules used to manage the groups of information and their names is called a "file system".

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    +1 for "storage". I think this is the way things are headed. Commented Aug 12, 2015 at 17:12

Computing terminology is full of anachronisms. See the picture below. It comes from my Microsoft Word 2013 edition.

enter image description here

That is a perfect picture of a floppy disk! You won't see one of those outside of a museum now.

I think that a lot of the time we just pick up a word and its meaning without thinking about it. Eventually someone comes up with the ideal term and we just switch overnight.

Example - In Britain for many years we didn't know what to call the thing that changes the channel on your TV. It had various unsatisfactory names, e.g. 'zapper'. One day someone called it a 'remote' and now everyone does.

Because technology moves so fast, I don't think it matters if popular terminology fails to keep up.

If I want to buy a Solid State Drive, I go into a shop and ask for a SSD. However if I asked for an SSD drive or even an SSD disk, I'm sure they would still take my money.

  • "Zapper". That's awesome. Commented Aug 13, 2015 at 17:08
  • That "clicker" in your hand is called a "wand".
    – ebyrob
    Commented Jan 6, 2017 at 18:04

'Disk' may technically be a misnomer, but so was referring to the 3.5 inch disks as 'floppy disks' (they weren't floppy at all - 'floppy' was a holdover from the 5 1/4" and 9.5" removable disks which actually were floppy) and no one seemed to notice.

So, I think in a case like this, as long as your audience still understands your intent then I don't think there's an issue. If it helps, in the IT world, it is still acceptable to refer to SSDs as disks.

However, if you're definitely wanting a new word, that isn't a misnomer, then 'hard drive' should work. I would avoid your other options for the reasons that follow:

  • File System - wouldn't work because technically it refers to the technology used to define and map out memory into a technology that contains files and folders and links to other files and folders, as well as links to other storage devices. NTFS and HFS are both file systems, these are different file system styles used when formatting new hard drives.

  • Persistent Storage - won't work because SSDs aren't persistent at all. They're meant to be rewritten. They're persistent until they've been overwritten, but it's easy to overwrite. Also, SSD drives eventually suffer from information degradation from ambient radiation rotting individual bits of information. BluRays and DVDs are more persistent.

  • Mass Storage - refers to large, generally immovable, clusters of data, which has less to do with the type of storage technology - since mass storage can be a combination of spinning disks and SSD technology; more to the point, most mass storage solutions still use spinning disk tech because it's cheaper than SSD tech.

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    3.5 inch disks were just as floppy as 5.25 inch disks. The rigid part was just the protective case around the actual disk. Commented Aug 11, 2015 at 22:37
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    SSDs are persistent. The data persists as long as you want. Contrast this with RAM, which is erased when you lose power. Before SSDs and other similar tech, PDAs, the ancestors of smartphones, would lose all data if they lost power. That's why you synchronized your Palm Pilot daily. Commented Aug 12, 2015 at 16:59
  • What @Mr. Shiny and New said. Doubtless if you monitor a lot of ssd's over a long time, you'll find a few failures due to ambient radiation. But mostly they'll fail because of physical degradation of materials (caused only by rewriting with new values, I believe; repeated reads don't affect stability). Commented Aug 12, 2015 at 17:39

Coming back to the question for a second time. I see an answer staring me in the face. Several people have already used the phrase in passing.

HDDs, SSDs and so on are all storage devices. If you want to add 'persistent' then that's fine as well.


You should consider where you are using this terminology and what you are trying to convey with it. Are you suggesting the user save a file to their device? to their cloud storage? Are they downloading a file? Is their device a computer, a smartphone, maybe either?

Now that computing is everywhere, but the technology for storing data is changing drastically faster than it used to, and the number of people writing applications, documentation, etc, is much larger than in the past, you might find that there isn't a standard term that works as well as disk used to.

Some examples:

  • Save to your device <- Some people would object to their computer being called this, but would accept it for a phone or tablet
  • Save to disk <- Many devices don't have disks
  • Save to local storage <- Assuming the storage is local
  • Save to cloud storage <- Assuming the storage is "in the cloud"
  • Save <- Save where?

Using specific terminology like file system, SD Card, SSD, flash, USB, etc, is problematic. Maybe the storage doesn't use that technology. You are better off trying to describe the storage based on where it is: built-in to the device, attached but removable, on a network. However, you may not always be able to tell if storage is one of those things. My G: is a removable USB HDD and my Y: is a network-attached drive but my computer treats those all (in some respects) as local storage. Certainly they are distinct from the Google Drive account I have, where I can also save files. But at least if my program offers to save it to my computer (or to my "device") I know it will put it on whatever storage medium I'm using. The software doesn't care anyway.


If I take a software user's view, I don't care where the information is unless:

  1. I want to put it into a particular place (thumb drive, cloud, file system, Internet, etc.)
  2. I need to know some special incantation to retrieve the information at a future time, or to restart or continue the program with this information.
  3. I get an error message and need to know how to recover.

For a lot of applications (e.g., my mobile phone address book, the cruise control in my car) the answer to all of these questions is irrelevant to me. So I'd vote for not using any such term in software documentation unless one or more of the three situations above applies. And if so, consider changing the way your software works!


If this is software documentation for an end user, I would say, keep it as simple as possible.

Why would an end user have to be concerned about the internals of the machine?

SSD? Disk? Storage Device? Help!

To advance the lawn mower, press the gas pedal. The gas pedal is linked to the carburetor. There are different kinds of carburetors. Make sure to know what kind of carburetor is in your lawnmower. Some carburetors...

The user just wants to cut the grass.

What's important is that the end user can translate his intention to the functionality of the software, perform actions and interpret results (expected vs. not expected.)

It would be nice if you could even avoid all the verbs "Open", "Close", "Save", etc. These are operating system functions. Perhaps they could be mentioned once, at the most, to indicate that this software uses the "classic" paradigm of the file system (as opposed to the mobile paradigm where the file system is invisible).

If necessary, you could provide some information about the internals of the computer in a short appendix or in "Did you know?" sidebars.

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