Glossary

Write Amplification

When one logical write causes several physical writes under the hood.

1 min read·4 sections
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Definition

When one logical write causes several physical writes under the hood.

How it works

An LSM-tree rewrites data repeatedly during compaction; SSDs rewrite whole blocks; replication and WALs multiply it further. High write amplification burns disk bandwidth and wears out SSDs. It's the main cost LSM trees pay for fast sequential writes, and a key tuning trade-off against read and space amplification.

Common questions

What is Write Amplification?

When one logical write causes several physical writes under the hood.

How does Write Amplification work?

An LSM-tree rewrites data repeatedly during compaction; SSDs rewrite whole blocks; replication and WALs multiply it further. High write amplification burns disk bandwidth and wears out SSDs. It's the main cost LSM trees pay for fast sequential writes, and a key tuning trade-off…

What is Write Amplification used for in system design?

An LSM-tree rewrites data repeatedly during compaction; SSDs rewrite whole blocks; replication and WALs multiply it further. High write amplification burns disk bandwidth and wears out SSDs. It's the main cost LSM trees pay for fast sequential writes, and a key tuning trade-off…

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