Cookbook recipe

Emergency recovery when the disk is full

Applies to PostgreSQL 13–17 Last reviewed May 2026 Grounded in source

What This Is

A production experience capsule based on real incident patterns.

Why It Matters

Builds production judgment under pressure.

Next Step

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Estimated investigation4 min

Scenario

The data disk hit 100% and PostgreSQL is throwing "No space left on device" or has stopped. Recover without making it worse. Diagnose it Confirm what is consuming space: -- from the OS: -- du -sh…

Investigation Path

The data disk hit 100% and PostgreSQL is throwing “No space left on device” or has stopped. Recover without making it worse.

Diagnose it

Confirm what is consuming space:

-- from the OS:
-- du -sh /var/lib/pgsql/data/*
SELECT slot_name, active FROM pg_replication_slots;

Why it happens

Common culprits: runaway WAL from an inactive replication slot or failing archiver, a massive temp file from a bad query, or log files. The cluster halts writes to avoid corruption.

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Career Impact

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Related & next steps

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Concepts on this page

Replication
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