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Aether Environment Variables

Organized by subsystem. Each variable has a short description and status.

Status legend: active | experimental | active-or-experimental | planned-not-wired | present-needs-improvement

Audience legend: production/user | development/test | mixed

Audience Quick Index​

Production/User sections: Aether Cache, Aether Journal, Aether Logging, Aether Bridge, Aether Core, Changefeed Telemetry, Write-Ahead Cache, Moka L1 Cache, Cache/WAL Legacy Controls, Storage I/O & RocksDB, Adaptive Monitoring.

Development/Test sections: none currently.

Mixed sections (contains both production/user and development/test flags): Aether Transport, Storage Backend Selection, FUSE/Runtime Debug, Misc.

Aether Cache (production/user)​

AFS_AETHER_CACHE_DIR - Base cache root; session content lives under <cache>/<session>/content/. See AFS_AETHER_CACHE_DIR deep dive. [active] AFS_AETHER_CACHE_DIRTY_HIGH_WATER_BYTES - Dirty-byte threshold that engages cache backpressure. See AFS_AETHER_CACHE_DIRTY_HIGH_WATER_BYTES deep dive. [active] AFS_AETHER_CACHE_DIRTY_LOW_WATER_BYTES - Dirty-byte threshold that clears cache backpressure. See AFS_AETHER_CACHE_DIRTY_LOW_WATER_BYTES deep dive. [active] AFS_AETHER_CACHE_DIRTY_MAX_BYTES - Hard cap for dirty cache bytes (0 disables). See AFS_AETHER_CACHE_DIRTY_MAX_BYTES deep dive. [active] AFS_AETHER_CACHE_DISK_HIGH_FREE_BYTES - Free-disk-bytes threshold that clears cache backpressure. See AFS_AETHER_CACHE_DISK_HIGH_FREE_BYTES deep dive. [active] AFS_AETHER_CACHE_DISK_HIGH_FREE_PERCENT - Free-disk-percent threshold that clears cache backpressure. See AFS_AETHER_CACHE_DISK_HIGH_FREE_PERCENT deep dive. [active] AFS_AETHER_CACHE_DISK_LOW_FREE_BYTES - Free-disk-bytes threshold that engages cache backpressure. See AFS_AETHER_CACHE_DISK_LOW_FREE_BYTES deep dive. [active] AFS_AETHER_CACHE_DISK_LOW_FREE_PERCENT - Free-disk-percent threshold that engages cache backpressure. See AFS_AETHER_CACHE_DISK_LOW_FREE_PERCENT deep dive. [active] AFS_AETHER_CACHE_MAX_BYTES - Hard cap for clean cache bytes (0 disables). See AFS_AETHER_CACHE_MAX_BYTES deep dive. [active] AFS_AETHER_CACHE_SHARED_ROOT - Host-wide shared blob root for cross-session dedupe via hard-links (default <cache_dir>/shared; set off|none|disabled|false|0 to disable). See AFS_AETHER_CACHE_SHARED_ROOT deep dive. [active]

Aether Journal (production/user)​

AFS_AETHER_JOURNAL_CLEAR_AGE_SECS - Oldest journal-entry age low-water mark that clears backpressure. See AFS_AETHER_JOURNAL_CLEAR_AGE_SECS deep dive. [active] AFS_AETHER_JOURNAL_HIGH_WATER_BYTES - Journal backlog bytes high-water mark that engages backpressure. See AFS_AETHER_JOURNAL_HIGH_WATER_BYTES deep dive. [active] AFS_AETHER_JOURNAL_HIGH_WATER_ENTRIES - Journal backlog entry-count high-water mark that engages backpressure. See AFS_AETHER_JOURNAL_HIGH_WATER_ENTRIES deep dive. [active] AFS_AETHER_JOURNAL_LOW_WATER_BYTES - Journal backlog bytes low-water mark that clears backpressure. See AFS_AETHER_JOURNAL_LOW_WATER_BYTES deep dive. [active] AFS_AETHER_JOURNAL_LOW_WATER_ENTRIES - Journal backlog entry-count low-water mark that clears backpressure. See AFS_AETHER_JOURNAL_LOW_WATER_ENTRIES deep dive. [active] AFS_AETHER_JOURNAL_MAX_AGE_SECS - Oldest journal-entry age high-water mark that engages backpressure. See AFS_AETHER_JOURNAL_MAX_AGE_SECS deep dive. [active] AFS_AETHER_JOURNAL_SYNC_BACKLOG_BYTES - Early WAL sync trigger when pending appended bytes exceed this threshold. See AFS_AETHER_JOURNAL_SYNC_BACKLOG_BYTES deep dive. [active] AFS_AETHER_JOURNAL_SYNC_INTERVAL_MS - Timer interval for journal WAL sync in interval mode. See AFS_AETHER_JOURNAL_SYNC_INTERVAL_MS deep dive. [active] AFS_AETHER_JOURNAL_SYNC_POLICY - Journal WAL sync policy: immediate, manual, or interval. See AFS_AETHER_JOURNAL_SYNC_POLICY deep dive. [active]

Aether Logging (production/user)​

AFS_AETHER_LOG - Primary Aether log level. See AFS_AETHER_LOG deep dive. [active] AFS_AETHER_LOG_DESTINATION - Log destination (stderr/stdout/file). See AFS_AETHER_LOG_DESTINATION deep dive. [active] AFS_AETHER_LOG_FORMAT - Log output format (for example json/text). See AFS_AETHER_LOG_FORMAT deep dive. [active] AFS_AETHER_LOG_PATH - Log file path when file logging is enabled. See AFS_AETHER_LOG_PATH deep dive. [active] AFS_AETHER_LOG_REDACT - Log redaction mode for sensitive values. See AFS_AETHER_LOG_REDACT deep dive. [active] AFS_AETHER_LOG_REDACT_SALT - Optional salt used by hash-based log redaction. See AFS_AETHER_LOG_REDACT_SALT deep dive. [active] AFS_AETHER_LOG_ROTATION - Log rotation strategy. See AFS_AETHER_LOG_ROTATION deep dive. [active] AFS_AETHER_LOG_ROTATION_MAX_BYTES - Size-based log rotation threshold in bytes. See AFS_AETHER_LOG_ROTATION_MAX_BYTES deep dive. [active] AFS_AETHER_LOG_ROTATION_MAX_FILES - Maximum retained rotated log files. See AFS_AETHER_LOG_ROTATION_MAX_FILES deep dive. [active] AFS_AETHER_LOG_SAMPLE_INVALIDATION - Sampling divisor for invalidation debug logs. See AFS_AETHER_LOG_SAMPLE_INVALIDATION deep dive. [active] AFS_AETHER_LOG_SAMPLE_PREFETCH - Sampling divisor for prefetch debug logs. See AFS_AETHER_LOG_SAMPLE_PREFETCH deep dive. [active]

Aether Transport (mixed)​

AFS_AETHER_TRANSPORT_CONN_WINDOW_BYTES - Transport connection-level flow-control window in bytes. See AFS_AETHER_TRANSPORT_CONN_WINDOW_BYTES deep dive. [active] AFS_AETHER_TRANSPORT_HEARTBEAT_INTERVAL_MS - Transport heartbeat interval in milliseconds. See AFS_AETHER_TRANSPORT_HEARTBEAT_INTERVAL_MS deep dive. [active] AFS_AETHER_TRANSPORT_IDLE_TIMEOUT_MS - Transport idle timeout in milliseconds. See AFS_AETHER_TRANSPORT_IDLE_TIMEOUT_MS deep dive. [active] AFS_AETHER_TRANSPORT_STREAM_WINDOW_BYTES - Transport stream-level flow-control window in bytes. See AFS_AETHER_TRANSPORT_STREAM_WINDOW_BYTES deep dive. [active] AFS_AETHER_TRANSPORT_QLOG_DIR - Directory for transport qlog output files. [experimental] AFS_AETHER_TRANSPORT_QLOG_ENABLE - Enable transport qlog tracing. [experimental]

Aether Bridge (production/user)​

AFS_AETHER_RECONNECT_JITTER_PERCENT - Bridge reconnect jitter percentage. See AFS_AETHER_RECONNECT_JITTER_PERCENT deep dive. [active] AFS_AETHER_RECONNECT_MAX_MS - Maximum bridge reconnect backoff delay (ms). See AFS_AETHER_RECONNECT_MAX_MS deep dive. [active] AFS_AETHER_RECONNECT_MULTIPLIER - Bridge reconnect exponential multiplier. See AFS_AETHER_RECONNECT_MULTIPLIER deep dive. [active] AFS_AETHER_RECONNECT_START_MS - Initial bridge reconnect backoff delay (ms). See AFS_AETHER_RECONNECT_START_MS deep dive. [active] AFS_AETHER_SERVER_ENDPOINT - Bridge server endpoint URL. See AFS_AETHER_SERVER_ENDPOINT deep dive. [active] AFS_AETHER_WORKER_ID - Bridge worker ID. See AFS_AETHER_WORKER_ID deep dive. [active]

Aether Core (production/user)​

AFS_AETHER_CLIENT_METRICS_ADDR - Bind address for Aether client metrics endpoint. See AFS_AETHER_CLIENT_METRICS_ADDR deep dive. [active] AFS_AETHER_CONFIG - Path to aether.toml config file. See AFS_AETHER_CONFIG deep dive. [active] AFS_AETHER_CONTROL_SOCKET - Path for the local control socket. See AFS_AETHER_CONTROL_SOCKET deep dive. [active] AFS_AETHER_DIR_CACHE_TTL_SECS - Time interval in seconds for dir cache ttl secs. See AFS_AETHER_DIR_CACHE_TTL_SECS deep dive. [active] AFS_AETHER_DISABLE - Disable Aether mount path and exit early. See AFS_AETHER_DISABLE deep dive. [active] AFS_AETHER_ENABLE_RANGE_CACHE - Enable or disable LocalEngine cache-index range reads on the read path (true by default). See AFS_AETHER_ENABLE_RANGE_CACHE deep dive. [active] AFS_AETHER_LOOKUP_TTL_SECS - Time interval in seconds for lookup ttl secs. See AFS_AETHER_LOOKUP_TTL_SECS deep dive. [active] AFS_AETHER_MOUNT_OPTIONS - Comma-separated key/key=value mount tokens forwarded to Aether mount-flag validation and fuse3 mount option construction (unsupported/invalid tokens are ignored with warnings). See AFS_AETHER_MOUNT_OPTIONS deep dive. [active] AFS_AETHER_NEGATIVE_LOOKUP_TTL_SECS - Time interval in seconds for negative lookup ttl secs. See AFS_AETHER_NEGATIVE_LOOKUP_TTL_SECS deep dive. [active] AFS_AETHER_READ_ONLY - Force read-only mount/runtime behavior. See AFS_AETHER_READ_ONLY deep dive. [active] AFS_AETHER_SHUTDOWN_TIMEOUT_SECS - Time interval in seconds for shutdown timeout secs. See AFS_AETHER_SHUTDOWN_TIMEOUT_SECS deep dive. [active] AFS_AETHER_DISPATCH_CAPACITY - Parsed/validated dispatcher capacity knob; currently accepted for forward compatibility but not enforced by the active mount dispatcher path. [experimental] AFS_AETHER_DISPATCH_MAX_WRITE_STREAK - Parsed/validated dispatcher write-fairness knob; currently accepted for forward compatibility but not enforced by the active mount dispatcher path. [experimental] AFS_AETHER_FUSE_QUEUE_TIMEOUT_MS - Parsed/validated dispatcher queue-timeout knob; currently accepted for forward compatibility but not enforced by the active mount dispatcher path. [experimental]

Changefeed Telemetry (production/user)​

AFS_TELEMETRY_CHANGEFEED_ALLOW_SENSITIVE_IDENTIFIERS - Controls telemetry changefeed allow sensitive identifiers. See AFS_TELEMETRY_CHANGEFEED_ALLOW_SENSITIVE_IDENTIFIERS deep dive. [active] AFS_TELEMETRY_CHANGEFEED_ENABLED - Enable or disable telemetry changefeed enabled. See AFS_TELEMETRY_CHANGEFEED_ENABLED deep dive. [active] AFS_TELEMETRY_CHANGEFEED_FORCE_QA - Controls telemetry changefeed force qa. See AFS_TELEMETRY_CHANGEFEED_FORCE_QA deep dive. [active] AFS_TELEMETRY_CHANGEFEED_MAX_MEMORY_BYTES - Byte-size limit/threshold for telemetry changefeed max memory bytes. See AFS_TELEMETRY_CHANGEFEED_MAX_MEMORY_BYTES deep dive. [active] AFS_TELEMETRY_CHANGEFEED_MIN_SAMPLING_RATE - Rate setting for telemetry changefeed min sampling rate. See AFS_TELEMETRY_CHANGEFEED_MIN_SAMPLING_RATE deep dive. [active] AFS_TELEMETRY_CHANGEFEED_QA_SAMPLING_RATE - Rate setting for telemetry changefeed qa sampling rate. See AFS_TELEMETRY_CHANGEFEED_QA_SAMPLING_RATE deep dive. [active] AFS_TELEMETRY_CHANGEFEED_REDACTION_MODE - Mode/policy setting for telemetry changefeed redaction mode. See AFS_TELEMETRY_CHANGEFEED_REDACTION_MODE deep dive. [active] AFS_TELEMETRY_CHANGEFEED_REDACTION_SALT - Controls telemetry changefeed redaction salt. See AFS_TELEMETRY_CHANGEFEED_REDACTION_SALT deep dive. [active] AFS_TELEMETRY_CHANGEFEED_RING_BUFFER_SIZE - Capacity/size setting for telemetry changefeed ring buffer size. See AFS_TELEMETRY_CHANGEFEED_RING_BUFFER_SIZE deep dive. [active] AFS_TELEMETRY_CHANGEFEED_SAMPLING_RATE - Rate setting for telemetry changefeed sampling rate. See AFS_TELEMETRY_CHANGEFEED_SAMPLING_RATE deep dive. [active] AFS_TELEMETRY_CHANGEFEED_TENANT_ALLOWLIST - Controls telemetry changefeed tenant allowlist. See AFS_TELEMETRY_CHANGEFEED_TENANT_ALLOWLIST deep dive. [active] AFS_TELEMETRY_CHANGEFEED_TENANT_ID - Identifier for telemetry changefeed tenant ID. See AFS_TELEMETRY_CHANGEFEED_TENANT_ID deep dive. [active] AFS_TELEMETRY_RETENTION_DIR - Directory path for telemetry retention dir. See AFS_TELEMETRY_RETENTION_DIR deep dive. [active] AFS_TELEMETRY_RETENTION_ENABLED - Enable or disable telemetry retention enabled. See AFS_TELEMETRY_RETENTION_ENABLED deep dive. [active] AFS_TELEMETRY_RETENTION_FILE_PREFIX - Controls telemetry retention file prefix. See AFS_TELEMETRY_RETENTION_FILE_PREFIX deep dive. [active] AFS_TELEMETRY_RETENTION_MAX_AGE_HOURS - Time interval in hours for telemetry retention max age hours. See AFS_TELEMETRY_RETENTION_MAX_AGE_HOURS deep dive. [active] AFS_TELEMETRY_RETENTION_MAX_FILE_BYTES - Byte-size limit/threshold for telemetry retention max file bytes. See AFS_TELEMETRY_RETENTION_MAX_FILE_BYTES deep dive. [active] AFS_TELEMETRY_RETENTION_MAX_HISTORY_FILES - Controls telemetry retention max history files. See AFS_TELEMETRY_RETENTION_MAX_HISTORY_FILES deep dive. [active]

Moka L1 Cache (production/user)​

AFS_MOKA_L1_TTI_SECS - Time interval in seconds for moka L1 tti secs. See AFS_MOKA_L1_TTI_SECS deep dive. [active] AFS_MOKA_L1_TTL_SECS - Time interval in seconds for moka L1 ttl secs. See AFS_MOKA_L1_TTL_SECS deep dive. [active] AFS_MOKA_MAX_DIRTY_COUNT - Count limit for moka max dirty count. See AFS_MOKA_MAX_DIRTY_COUNT deep dive. [active] AFS_MOKA_TIER_BUDGETS - Controls moka tier budgets. See AFS_MOKA_TIER_BUDGETS deep dive. [active]

Cache/WAL Legacy Controls (production/user)​

AFS_CACHE_INDEX_BLOOM_BITS_PER_KEY - Controls cache index bloom bits per key. See AFS_CACHE_INDEX_BLOOM_BITS_PER_KEY deep dive. [active] AFS_CACHE_INDEX_COMPACTION_READAHEAD_BYTES - Byte-size limit/threshold for cache index compaction readahead bytes. See AFS_CACHE_INDEX_COMPACTION_READAHEAD_BYTES deep dive. [active] AFS_CACHE_INDEX_DIRTY_MAX_BYTES_FOR_LEVEL_BASE_MB - Megabyte-size limit/threshold for cache index dirty max bytes for level base mb. See AFS_CACHE_INDEX_DIRTY_MAX_BYTES_FOR_LEVEL_BASE_MB deep dive. [active] AFS_CACHE_INDEX_DIRTY_TARGET_FILE_SIZE_MB - Megabyte-size limit/threshold for cache index dirty target file size mb. See AFS_CACHE_INDEX_DIRTY_TARGET_FILE_SIZE_MB deep dive. [active] AFS_CACHE_INDEX_LEVEL0_COMPACTION_TRIGGER - Controls cache index level0 compaction trigger. See AFS_CACHE_INDEX_LEVEL0_COMPACTION_TRIGGER deep dive. [active] AFS_CACHE_INDEX_LEVEL0_SLOWDOWN_TRIGGER - Controls cache index level0 slowdown trigger. See AFS_CACHE_INDEX_LEVEL0_SLOWDOWN_TRIGGER deep dive. [active] AFS_CACHE_INDEX_LEVEL0_STOP_TRIGGER - Controls cache index level0 stop trigger. See AFS_CACHE_INDEX_LEVEL0_STOP_TRIGGER deep dive. [active] AFS_CACHE_INDEX_POINT_LOOKUP_OPTIMIZATION - Controls cache index point lookup optimization. See AFS_CACHE_INDEX_POINT_LOOKUP_OPTIMIZATION deep dive. [active] AFS_CACHE_INDEX_RANGE_MAX_BYTES_FOR_LEVEL_BASE_MB - Megabyte-size limit/threshold for cache index range max bytes for level base mb. See AFS_CACHE_INDEX_RANGE_MAX_BYTES_FOR_LEVEL_BASE_MB deep dive. [active] AFS_CACHE_INDEX_RANGE_TARGET_FILE_SIZE_MB - Megabyte-size limit/threshold for cache index range target file size mb. See AFS_CACHE_INDEX_RANGE_TARGET_FILE_SIZE_MB deep dive. [active]

Storage I/O & RocksDB (production/user)​

AFS_IO_URING_BATCH_SIZE - Capacity/size setting for I/O uring batch size. See AFS_IO_URING_BATCH_SIZE deep dive. [active] AFS_IO_URING_CQ_WAIT_MS - Time interval in milliseconds for I/O uring cq wait ms. See AFS_IO_URING_CQ_WAIT_MS deep dive. [active] AFS_IO_URING_FIXED_BUFFERS - Number of io_uring fixed buffers. See AFS_IO_URING_FIXED_BUFFERS deep dive. [active] AFS_IO_URING_KERNEL_POLL - Controls io_uring kernel polling mode. See AFS_IO_URING_KERNEL_POLL deep dive. [active] AFS_IO_URING_QUEUE_DEPTH - Controls io_uring queue depth. See AFS_IO_URING_QUEUE_DEPTH deep dive. [active] AFS_IO_URING_SQ_THREAD_IDLE_MS - Time interval in milliseconds for io_uring sq thread idle ms. See AFS_IO_URING_SQ_THREAD_IDLE_MS deep dive. [active] AFS_ROCKSDB_USE_DIRECT_READS - Controls rocksdb use direct reads. See AFS_ROCKSDB_USE_DIRECT_READS deep dive. [active] AFS_ROCKSDB_USE_DIRECT_WRITES - Controls rocksdb use direct writes. See AFS_ROCKSDB_USE_DIRECT_WRITES deep dive. [active] AFS_ROCKSDB_USE_IO_URING - Controls rocksdb use I/O uring mode. See AFS_ROCKSDB_USE_IO_URING deep dive. [active]

Storage Backend Selection (mixed)​

AFS_BENCH_BACKEND - Controls benchmark storage backend selection (rocksdb or memory when compiled). See AFS_BENCH_BACKEND deep dive. [active] [development/test] AFS_STORAGE_BACKEND - Controls storage backend selection (rocksdb or memory) for runtime and storage-maintenance commands. See AFS_STORAGE_BACKEND deep dive. [active] [production/user] AFS_STORAGE_READ_ONLY - Opens storage backends in read-only mode for storage-maintenance commands. See AFS_STORAGE_READ_ONLY deep dive. [active] [production/user] AFS_TEST_BACKEND - Selects backend used by test helpers/compliance harnesses. See AFS_TEST_BACKEND deep dive. [active] [development/test]

FUSE/Runtime Debug (mixed)​

AFS_FUSE_METRICS_ADDR - Network address/endpoint for fuse metrics addr. [active] [production/user]

Misc (mixed)​

AFS_JOURNAL_BENCH_ENTRY_COUNT - Count limit for journal bench entry count. [active] [development/test]