[LINUX] Summary of restrictions by file system
1. Contents of this article
The correspondence between the file system type and the OS and the restrictions are organized.
The file system is one of the functions provided by the OS, and is a function required for managing and operating data stored in storage devices such as HDDs and USB memory. FAT32, exFAT, NTFS, etc. can be specified when formatting, but the supported formats differ depending on the OS.
For example, FAT32 is compatible with many operating systems such as Windows, Mac, Linux, and raspbian, so if you use a storage device formatted with FAT32, you can transfer data between personal computers. However, note that there are restrictions on the size limit of one file and the number of files that can be stored in one folder for each file system.
The sites referred to in the survey of this article are listed in the related links at the bottom of the page.
2. List of correspondence between file system types and OS
I investigated FAT32, exFAT, NTFS, and ext4, which I often use personally.
RW: Read / write RO: Read only ×: Not supported
| File system | Windows | Mac | Linux | Volume size | Maximum size of 1 file | Maximum number of files in one directory |
|---|---|---|---|---|---|---|
| FAT32 | RW | RW | RW | 2TiB * 32GiB on Windows |
4GiB | 65,535（※1） |
| exFAT | RW | RW | × | 64ZiB | 16EiB | 2,796,202 |
| NTFS | RW | × | × | 16EiB | 16EiB | 4,294,967,295 |
| ext4 | × | × | RW | 1EiB | 16TiB | i-nodedependent upon |
- 1: The number of files when the file name conforms to the 8.3 format (file name (8 characters). Extension (3 characters)) and is the root directory. If the number of files is long or if it is a subdirectory, the number of files is suppressed.
| File name format | Root directory | Subdirectory | File name Remarks |
|---|---|---|---|
| 8.3 formats | 65,535 | 65,534 | Up to 12 characters for uppercase letters and symbols only |
| 13 characters | 65,535÷3→21,845 | 65,534÷3→21,844 | 小文字や数字含む13 charactersの例 |
| 25 characters | 65,535÷4→16,383 | 65,534÷4→16,383 | 小文字や数字含む25 charactersの例 |
3. In the end
When I tried to handle "2017 Test images [41K/6GB]" of COCO dataset on RaspberryPi, when I tried to copy to a USB memory formatted with FAT32, the following error occurred and the restrictions of FAT32 This survey was conducted because it was found that the number of files in one directory was exceeded.
I hope it will be helpful for those who have encountered similar problems.
-
Windows copy error (unexpected error, 0x80070052)
-
WSL file copy error ("cannot create regular file")
4. Related links
- Differences in file systems (FAT32, FAT16, NTFS, exFAT, HFS, HFS +, APFS)
- OS support status
- I tried to put together a Linux file system
- Tevibyte
- Maximum number of files per NTFS vol and FAT32 directory
- NTFS vs FAT vs exFAT
- Is There a Limit to What a Single Folder or Directory Can Hold?
- Maximum number of files that can be handled by the FAT32 file system is 65,535? 21,845 pieces?
- Is there a maximum number of files and capacity per directory on Ubuntu?
- Maximum number of stored files in linux (RHEL / CentOS / Amazon linux 2) directory
- File System and Storage Limits (https://access.redhat.com/ja/articles/1271503#ext4-7)
- About the Linux file system
Recommended Posts