A union filesystem is designed to allow multiple filesystems to be transparently merged into a single virtual filesystem. The primary purposes of a union filesystem include:
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Layering: It enables the stacking of different filesystems, allowing changes to be made to a read-only base layer without modifying it. This is useful for scenarios like live CD environments or container filesystems.
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Isolation: It provides a way to isolate changes made to files or directories, which can be beneficial for testing or development environments.
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Flexibility: Users can combine different filesystems, such as read-only and writable layers, to create a customized view of the data.
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Efficiency: It can help in saving disk space by allowing multiple users or applications to share the same base filesystem while maintaining their own changes.
Overall, union filesystems are useful in scenarios where you need to manage multiple versions or states of files without duplicating data.
