Answer
OverlayFS creates whiteout entries to hide files from lower layers without altering immutable layers.
Quick Answer
When a container modifies a file that exists in a lower read-only image layer, OverlayFS can't just modify it in place (the layer is read-only). So it copies the file up to the writable upper layer first, then modifies the copy. Whiteout files are special markers in the upper layer that indicate a file from a lower layer was deleted.
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SugharaIQ Editorial Team
Verified Answer
This answer has been peer-reviewed by industry experts holding senior engineering roles to ensure technical accuracy and relevance for modern interview standards.
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Source: SugharaIQ