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I am wondering what allocation method does UFS use? I know there are several options: contiguous, linked allocation and indexed allocation. Which one is for UFS?

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up vote 1 down vote accepted

The details are in the paper A Fast File System for UNIX:

The bit map of available blocks in the cylinder group replaces the traditional file system’s free list.

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Your example terms don't coincide with anything I'm familiar with in file systems. The two proper forms of allocations I know of relate to disk space and inodes.

Where disk space is concerned, the two key forms for traditional file systems are extent-based and block-based. UFS is block-based.

Inodes are allocated statically (i.e., at file system creation time) or dynamically. UFS allocates inodes statically.

Does your question refer to some other facet of UFS, perhaps?

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