---
title: "LMDB checkpoints of the memory state"
description: "The memory state is saved to an LMDB file four times a second. No client waits for it: it decides how much log a restart replays. Every value carries a checksum."
---

> Queen MQ documentation, for AI agents
> Complete self-contained summary of Queen MQ: https://queenmq.com/llms-brief.txt
> Fetch that first when the question is about the product rather than about this page.
> Index of all pages: https://queenmq.com/llms.txt

# LMDB checkpoints of the memory state

The state in memory is saved to an LMDB file, `store/data.mdb`, four times a second. This is a checkpoint, and no client waits for it: it only decides how much of the log a restart has to replay.

Every value carries a checksum, and the node checks all of them at boot. Every 6 hours a background scan reads the whole store again, to find damage before a restart does.

Traces have their own LMDB file, `traces/data.mdb`.

Source: https://queenmq.com/architecture/lmdb/index.mdx