Theodore Ts’o • 3/12/2009

Delayed allocation and the zero-length file problem

This technical article discusses the ext4 filesystem's delayed allocation feature, its performance benefits, and the 'zero-length file' problem that can cause data loss after a crash. It explains why applications relying on ext3's default 5-second commit behavior are at risk on ext4 if they don't properly use fsync() or fdatasync(). The post analyzes the underlying filesystem mechanics and the security trade-offs of different journaling modes.

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#linux #ext4 #fsync