Why does sequential disk I/O matter for write performance?
Sequential writes avoid disk-head seek time (5–10 ms per operation) by writing contiguously to the current position. A mechanical hard drive can sustain 100 MB/s sequentially but only 100–1,000 random I/O operations per second. LSM-trees exploit this massive speed difference to handle write-heavy workloads.
Answered in
LSM-Trees vs B-Trees: Why Cassandra Chose Sequential WritesB-trees seek random disk positions. LSM-trees buffer in memory and flush sequentially, converting random I/O into sequential writes for millions of ops/sec.
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