You may have noticed that Eagle libraries sometimes occupy significantly more storage space than the total size of the original files, potentially reaching twice the original size. This phenomenon is not an issue with the Eagle software itself, but is directly related to the "allocation unit size" setting of your hard drive.

Cause Analysis

Impact of Allocation Unit Size

"Allocation unit size" is the minimum unit used by the file system to allocate hard drive space. For storage scenarios like Eagle libraries that contain a large number of small files:

Small file storage efficiency: When using smaller allocation unit sizes (such as 4096 bytes), storage space can be utilized more effectively
Space waste issue: If the allocation unit is too large, even very small files will occupy the entire allocation unit's space

For example: A file that is only 1 KB in size, when stored on a hard drive with 32 KB allocation units, will actually occupy 32 KB of space, causing significant space waste.

Characteristics of Eagle Libraries

Eagle libraries contain many small JSON files and metadata files. When these files are stored on hard drives with larger allocation units, each file will occupy the complete allocation unit space, leading to a significant increase in overall space usage.

Solutions

If you find that your Eagle library is occupying abnormal amounts of space, you can consider the following methods:

Check current allocation unit size: Use system tools to view your hard drive's allocation unit settings
Adjust allocation unit size: When formatting your hard drive, choose a smaller allocation unit size (such as 4096 bytes) for the partition storing your Eagle library
Balance speed and space: Note that allocation unit size also affects file reading speed, so you need to find a balance between space utilization and reading efficiency

Important Notes

Adjusting allocation unit size requires formatting the hard drive, so please be sure to backup important data first
4096 bytes (4 KB) allocation unit size is usually the ideal choice for storing large numbers of small files
Default allocation unit sizes may vary across different operating systems

Reference:

/support/article/why-does-eagle-library-take-up-more-space-than-original-files

Why does the Eagle library take up more space than the original files?