The answer is simple. The “lost space” is reserved for the file system as well as the device’s operating system/device information if it exists.
When we buy a data device (a USB Flash drive for example), we expect that it can hold as much data as the design data capacity printed on its label and packaging. After some time upon opening its packaging, we get disappointed that it can’t hold as much data as we expect them to be. In the end, we might have regretted that we might have bought another one.
What formatted capacity will I get from buying a 2GB storage device?
From my experience, buying a 2GB USB Flash Drive won’t give you a full 2.00 GB of free storage, but instead, will give you 1.86GB worth of data storage when formatted with System 32 file system. Some of us might thinking that the manufacturers might be tricking by not giving us a device our money is worth for; however, most of us accept this fact and mind nothing about it.
Is it possible to get that full capacity?
If you think getting that full capacity is possible, its possible. However, it will be just a plain unallocated space and will be unusable by any system. Moreover, it’s useless unless it is formatted.
Therefore, manufacturers are deceiving me?
Nope. No company has ever sold a data storage device that has exactly the same formatted capacity as the printed capacity on its label and packaging. If they do, they might be deceiving you. Most data storage manufacturers actually ship their products and devices with exactly the same number of bytes present on their device as indicated on its label and packaging. Manufacturers know and accept the fact that its actual formatted capacity is less than what is advertised. Here is a description Apple indicated on its iPhone website:
** 1GB = 1 billion bytes; actual formatted capacity less.
I understand, what will they do with that missing space?
As what is said in the beginning of this article, here are the following reasons why that “missing space” is reserved.
A. It is reserved for file system that device is formatted with.
A file system use indexes where they store information where your files and folders are located in a disk or drive. It also serves like a card catalog inside a library. You use it to locate books and information easily by going directly into its designated shelf and location. If you remove the card catalogs or computer-catalogs inside a library, you will have difficulty in finding a particular book by manually looking at every book present in a library. Plus, it’s a time-consuming behavior. Same applies to a disk without a file system or catalog system.
B. It is also where some manufacturer and device information is stored.
Some of its stored data include the manufacturer name, product type, kind, model, part number, serial number, hardware id, and a lot more. Windows and any other operating systems use this information to determine which device drivers and services are to be launched. Once a communication between your device and the computer is established, you can read, write, modify any of its contents and format it. Manufacturers also use this information for verification that their software designed for that device will work perfectly with your device. If any of these information is not present or read properly. Windows will report a “USB device not recognized.” error message.
C. Is is where the device operating system, system files and reserved space are stored.
If your device is designed primarily for storing data only and nothing else, most probably is that it doesn’t a reserved operating systems. These data storage devices include some USB Flash Disk, CD, DVD, BD, Hard disk, SSD, memory cards, memory sticks and picture cards but they still possess other reasons above. Data storage devices that come with an operating system include mobile phones, portable media players and other gadgets. So, having an 8 GB capacity iPod Touch will leave you with 6.5 GB remaining free space while having a 32 or 64 GB of it will leave you 29 and 59 GB of free space respectively because iOS is reserved has reserved some space besides reasons above. Manufacturers store data in this location because it is secure and cannot be deleted or modified easily in case the user formats or erases the disk.
D. Other manufacturer reasons
Some manufacturers have other reasons why they reserve some of your disk’s capacity. One reason is for recovery space partition. You will not see that recovery partition appearing in your Explorer or Finder window because the manufacturer don’t want you to make changes into it. Even it does not show up, it occupies your hard drive capacity. This recovery partition is very essential especially when something goes wrong with your computer. You can make a fresh install of your operating system from it or use it to restore it to its out-of-the-box factory default.
These are my ideas and opinions on why we don't get a full formatted capacity from our devices. If there's something wrong with it, please feel free to leave a comment anonymously.