Where is the difference between SIZE and SIZE ON DISK

"Size"And"Size on disk" refers to the space occupied by a file on disk (HDD) and the actual file size. If you have a large volume folder (say over 2GB) in which you have stored many .doc, .txt, .php files, etc.… you will notice at “Properties” as the space occupied on disk of this folder (Size on disk) is greater than the actual volume of the files (Size).

In the image below we have the "Demo" folder which contains 67.155 files grouped in 8.958 folders. Size difference between "size"And"size on disk" is very large. Size: 3.17GB / Size on disk: 6.98GB.

Toshiba external HDD

The same "Demo" folder with almost the same number of files and folders (these differences can be ignored) but stoctat another HDD , we notice in the image below that the difference between "size" and "size on disk” is much smaller than in the previous case. Size: 3.17GB & Size on disk: 3.35GB.

local-hdd-date

How and Why the difference?

"Size" refers to actual file sizeAnd "Size on disk" refers to space on HDD of a file. Difference in volume "Size on disk” in the two examples above, is given by volume size units (cluster size) Of HDDs.
You probably noticed that when you want to format a partitionIf you choose NTFS, you have several options including "Allocation unit size”(Set to be the size of a unit a diskacquis - 512 bytes, 1024 bytes, 2048 bytes, 16 kilobytes, 32 kilobytes, 64 kilobytes, etc).

Cluster size

Okay let's say you set it up for an HDD partition 64 kilobytes / unit. Since these units are indivisibleAnd the unit can not be stored more files, if you have two small files of each 2 kilobytes (4 kilobytes in total) they will occupy on disk 128 kilobytes,
To save you as much space as possible disk, it is recommended that small files that are not currently used be archived (.zip, .rar).

This post will be continued soon with a tutorial that will be presented in detail an HDD component. Types of HDDATVs and technical details.

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2 thoughts on "Where is the difference between SIZE and SIZE ON DISK"

  1. Explain why no one understands this:
    “Well, let's say you set it up for a 64 kilobytes HDD partition / drive. Since these units are indivisible, the unit will not be able tomacadd more files, if you have two small files each 2 kilobytes (4 kilobytes in total) that will occupy 128 kilobytes disk,
    To save disk space, it is recommended that small files that are not routinely used be archived (.zip, .rar). ”

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  2. Hello, I am buying an SSD disk supposedly with a different capacity, but when it reaches 30gb, the next thing it grabs corruption, it grabs but it doesn't show video, and it doesn't recognize it. Formatted it NTFS and also exFAT with different drive configurations but nothing

    Reply
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