Is the USB flash drive exFAT formatted?What is the appropriate size for the formatted allocation unit?

In general, the smaller the formatted allocation unit, the more space you save.

The larger the allocation unit, the more time is saved, but the space is wasted.

It may seem that allocating small units saves space, but this is not the case.

The more blocks a file is split into, especially when those memory cells are scattered, the more time it takes to read the data.

The allocation unit size is the smallest unit that the system reads and writes to disks, and removable storage devices.

• Within the limit speed, the larger the size of the allocation unit, the faster the read/write speed, and vice versa.
• But here we must pay attention to a problem, the larger the allocated unit, the more space is wasted.
• In general, the size of an allocation unit can be arbitrary.
• However, the smaller the unit selection, the less space it takes to write to the end of the file, and vice versa.

What is the format allocation unit size?

When formatting a memory card (USB flash drive), select an allocation unit sized allocation unit (formerly known as a cluster).

• It is the amount of space allocated by the operating system for each unit address.
• When creating a partition, the option to allocate unit size is displayed.
• Only one file can be stored per allocation unit.

The file is divided into blocks and stored on disk according to the size of the allocation unit.

• For example, a file of size 512 bytes occupies 512 bytes of storage space when the allocation unit is 512 bytes;
• A file of size 513 bytes occupies 512 bytes of storage space when the allocation unit is 1024 bytes;
• But when the allocation unit is 4096, it will take up 4096 bytes of storage.

Assuming you format it as a 64K allocation unit:

• When you write a 130K file, the file occupies a space of 130/64=2.03.
• Since each cell can only write to the same data file, a 130K file actually occupies 3 cells.
• 3*64K=192K.When formatting a 16K allocation unit, this file occupies 130/16 = 8.13 of the SD card and occupies 9 units, 9 * 16K = 144K.

It can be seen from the above that the smaller the unit selection, the smaller the space occupied by the storage files, the less waste, and the higher the utilization rate of the SD card.

File System Features and Limitations

The following features and limitations of various file systems:

1. In FAT16 (Windows): support a maximum partition of 2GB and a maximum file size of 2GB;
2. FAT32 (Windows): supports partitions up to 128GB, and the maximum file size is 4G;
3. NTFS (Windows): supports a maximum partition size of 2TB and a maximum file size of 2TB (log-based features are not available for flash drives);
4. In exFAT (Windows): supports up to 16EB for partitions; maximum file size is 16EB (specially designed for flash drives);
5. HPFS (OS/2): supports a maximum partition of 2TB and a maximum file size of 2GB;
6. EXT2 and EXT3 (Linux): supports up to 4TB partition, the maximum file size is 2GB;
7. JFS (AIX): Support maximum partition 4P (block size = 4k), maximum file 4PB;
8. XFS (IRIX): This is a serious 64-bit filesystem that can support 9E (2 to 63 power) partitions.

How do I choose to format the allocation unit size?

• It is recommended to use default values ​​when formatting;
• The system will adjust the most matching default value without manual management;
• Then select Quick Format, which will take effect immediately.

Can a USB flash drive be formatted quickly?For details, please clickDownwardLink to understand the difference between quick format and normal format▼

Do U disks need quick formatting? The difference between quick formatting and normal full formatting

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