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Determining Block Liveness

Explore how log-structured file systems identify live data blocks using segment summary blocks that record inode numbers and offsets. Learn to verify block liveness by comparing disk addresses with inode mappings and understand efficiency improvements such as version number checks to optimize persistence and garbage collection processes.

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Segment summary block

Given a data block DD within an on-disk segment SS, LFS must be able to determine whether DD is live. To do so, LFS adds a little extra information to each segment that describes each block. Specifically, LFS includes, for each data block DD ...