---
title: "Reliability"
description: "MemoryReliabilityAdapter, FileReliabilityAdapter, and CloudflareReliabilityAdapter options."
---

> Documentation Index
> Fetch the complete documentation index at: https://logbun-docs.abshahin.workers.dev/llms.txt
> Use this file to discover all available pages before exploring further.

# Reliability

The public seam owns journal, DLQ lifecycle, recovery, statistics, lifecycle, and exclusive ownership. Methods: `init`, `close`, `appendJournal`, `acknowledgeJournal`, `recoverJournal`, `compactJournal`, `writeDlq`, `listDlq`, `claimDlq`, `settleDlqSuccess`, `settleDlqFailure`, `poisonDlq`, `requeueDead`, `deleteDead`, `readDlq`, `recoverOrphans`, `getStats`. `persistent` is a readonly boolean (`false` for memory).

Optional host-scheduler hooks: `pendingMaintenanceDelayMs()`, `requestMaintenance()`. Deprecated: `rearmMaintenance()`.

`recoverJournal` accepts `{ maxLogs?, maxBytes? }`. A finite `maxBytes` is strict: returned encoded records never exceed it, and an oversized first record yields zero logs with `truncated: true`. Finite negative values normalize to zero; non-finite values are treated as unbounded.

## MemoryReliabilityAdapter

Root default. `persistent: false`. No filesystem I/O.

```ts
import { MemoryReliabilityAdapter } from 'logbun';

new MemoryReliabilityAdapter({
  maxDlqEntries: 10_000,      // pending+processing cap; default 10_000
  enableJournal: false,       // in-process journal for tests; still lost on exit
  maxJournalEntries: 100_000, // used only when enableJournal is true
});
```

## FileReliabilityAdapter

Import from `logbun/durability/filesystem`. All filesystem options live here, not on `LogbunConfig`. Requires `namespace`.

| Adapter option | Default | Meaning |
|---|---:|---|
| `namespace` | required | Isolates data under `dataDir/namespace` (`[a-zA-Z0-9_-]{1,64}`) |
| `dataDir` | `.logbun` | Parent directory; `..` segments are rejected |
| `wal.fsync` | true | fsync journal appends / compaction |
| `wal.segmentBytes` | 16 MiB | WAL rotation threshold for `current.aof` → `seg-NNNNNN.aof` |
| `wal.compactAckThreshold` | 256 | Compact when this many ack ids sit in `acked.ids` |
| `wal.hardMaxBytes` | true | Refuse over-limit append with `wal_full` (equality is permitted) |
| `maxWalBytes` | 64 MiB | Journal size cap across current + segments |
| `dlq.fsync` | true | fsync DLQ writes / transitions |
| `dlq.maxEntries` | 10_000 | Pending + processing entry cap (`dlq_full`) |
| `encryptionKey` | — | AES-256-GCM; 32 bytes / 64-hex / base64-of-32; passphrases rejected |
| `instanceLock` | true | Exclusive namespace ownership |

This adapter does not schedule host wake-ups. Call `runMaintenance()` from the process.

Also exported from the filesystem subpath: `resolveLogbunDir` (alias `resolveDataDir`), `sanitizeNamespace`, `InstanceLock`, `InstanceLockError`, `WALStorage`, `DLQStorage`, `WAL_SIZE_SOFT_LIMIT_BYTES`, `WAL_SEGMENT_BYTES_DEFAULT`, `DLQ_MAX_FILES_DEFAULT`.

## CloudflareReliabilityAdapter

Import from `logbun/durability/cloudflare` **inside a SQLite-backed Durable Object**. ESM-only.

```ts
new CloudflareReliabilityAdapter({
  state: ctx,
  tablePrefix: 'logbun',
  maxJournalEntries: 100_000,
  maxDlqEntries: 10_000,
  scheduleAlarms: true,
  alarmDelayMs: 1_000,
});
```

The subpath re-exports `DurableAdmissionSchedulingError` and `isDurableAdmissionSchedulingError`. Also exports types `DurableObjectSqlStorage` and `DurableObjectStateLike`.

## `DLQEntry`

```ts
interface DLQEntry {
  id: string;
  state: 'pending' | 'processing' | 'dead';
  kind: 'pending' | 'processing' | 'dead'; // always equal to state
  tenantId: string | null;
  attempts: number;
  logCount: number;
  metadata?: Record<string, unknown>;
}
```

## Scheduling error

```ts
class DurableAdmissionSchedulingError extends Error {
  readonly durableAdmissionCommitted = true;
  // message: "durable admission committed but maintenance scheduling failed: …"
  name = 'DurableAdmissionSchedulingError';
}
```

Exported from `logbun` and from `logbun/durability/cloudflare`.

Source: https://logbun-docs.abshahin.workers.dev/reference/reliability/index.mdx