Tag
log-structured
- Jun 8, 2026 Segment Liveness Accounting: How the Cleaner Knows What Is Already Dead Maintaining a live-byte count per segment as blocks are superseded, why the count must be exact rather than sampled, and how indirect blocks make the decrement easy to get wrong. filesystems
- May 27, 2026 Splitting a Partition While Writes Continue The in-place split protocol: freeze, cut, publish, then let readers discover the new boundary. Why the split point is a durable record and why the parent must keep serving. distributed systems
- Nov 20, 2025 Inode Maps and Block Indirection: Finding Data That Never Stays in Place How a log-structured filesystem locates an inode whose address changes on every write, what the map costs per lookup, and why its cache is the deciding factor in read latency. filesystems
- Oct 9, 2025 The Log as the Filesystem: Segments, Sequential Writes, and the End of the Free-Space Map Why writing every block at the end of a log converts scattered small updates into large sequential transfers, and what replaces the allocator once nothing is ever overwritten in place. filesystems
- Jul 30, 2025 Decomposing Write Amplification in Log-Structured Filesystems The four terms that add up to bytes written per byte of user data, namely cleaning copies, checkpoint rewrites, summary overhead, and segment slack, and how each responds to segment size. filesystems
- Apr 30, 2025 The Circular Log: Head, Tail, and the Distance Between Them How an append-only log wraps around a finite volume, the segment state machine that makes wrapping safe, and why the gap between the write head and the reclaim frontier sets the achievable throughput. filesystems
- Mar 11, 2025 Data Temperature and the Cost of Cleaning Mixed Segments Why placing hot and cold data in the same segment forces the collector to copy live cold bytes to reclaim dead hot bytes, and how write segregation by expected lifetime bounds that cost. filesystems
- May 22, 2024 Choosing What to Clean: Greedy, Cost-Benefit, and Age-Ordered Segment Policies The three classical segment selection rules, the objective function each one optimizes, and why weighting freed space by the age of the data beats always cleaning the emptiest segment. filesystems
- Mar 14, 2024 Cleaner Interference and Foreground Latency in Append-Only Storage How a background collector steals device queue slots from the write path, why the resulting latency spikes are bursty rather than average, and the throttling and scheduling measures that bound them. filesystems
- Mar 5, 2024 Segment-Based Indexing and the Merge Operation Why search indexes are built as many small immutable segments rather than one mutable structure, and how the merge step reclaims dead postings and bounds segment count. information retrieval
- Nov 23, 2023 Checkpoint Regions and Tail Recovery in an Append-Only Log How a log-structured filesystem bounds what a crash can lose, and how it reconstructs the segment summaries written after the last durable checkpoint by scanning forward instead of backward. filesystems
- Oct 16, 2023 Garbage Collection Under Space Pressure: When Cleaning Cannot Outrun Writes What happens when a log-structured volume fills to the point that the collector must run in the foreground, why the reclaim rate collapses near full, and the reserved-capacity arithmetic that prevents it. filesystems