Why do many file systems pre-allocate a certain number of contiguous data blocks when a file is created?

Question

Accepted Answer

To guarantee at least some portion of the file will be stored contiguously and therefore reduce seeking in the middle of accessing its data.

Answer

Pre-allocation will ensure a higher TLB hit rate.

Answer

When inodes are assigned to a file, an error is thrown if the data blocks field is left null, so it must be set to something.

Answer

Each file needs to use a minimum number of data blocks, so the file system ensures this minimum number is allocated.

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