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flexFS

Metrics Reference

Both the metadata server (meta.flexfs) and the proxy server (proxy.flexfs) expose Prometheus metrics via an HTTP /metrics endpoint.

Metadata server metrics

Section titled “Metadata server metrics”

Namespace: flexfs_meta

RPC metrics

Section titled “RPC metrics”
MetricTypeLabelsDescription
flexfs_meta_rpc_ops_totalCountervolume_id, method, statusTotal RPC operations by method and status.
flexfs_meta_rpc_duration_secondsHistogramvolume_id, methodRPC operation latency in seconds.

Histogram buckets (seconds): 0.00001, 0.000025, 0.00005, 0.0001, 0.00025, 0.0005, 0.001, 0.0025, 0.005, 0.01, 0.025, 0.05, 0.1, 0.25, 0.5, 1, 2.5, 5, 10

Volume info metrics

Section titled “Volume info metrics”
MetricTypeLabelsDescription
flexfs_meta_volume_infoGaugevolume_id, volume_nameVolume metadata. Always 1 per volume; use labels to map IDs to names.

Volume gauge metrics

Section titled “Volume gauge metrics”
MetricTypeLabelsDescription
flexfs_meta_volume_blocksGaugevolume_idNumber of active blocks.
flexfs_meta_volume_blocks_retiredGaugevolume_idNumber of retired blocks.
flexfs_meta_volume_dentriesGaugevolume_idNumber of directory entries.
flexfs_meta_volume_inodesGaugevolume_idNumber of inodes.
flexfs_meta_volume_size_bytesGaugevolume_idTotal volume size in bytes.

Volume I/O counters

Section titled “Volume I/O counters”
MetricTypeLabelsDescription
flexfs_meta_volume_blocks_read_totalCountervolume_idTotal blocks read.
flexfs_meta_volume_blocks_written_totalCountervolume_idTotal blocks written.
flexfs_meta_volume_bytes_read_totalCountervolume_idTotal bytes read at FUSE boundary.
flexfs_meta_volume_bytes_written_totalCountervolume_idTotal bytes written at FUSE boundary.

Session metrics

Section titled “Session metrics”
MetricTypeLabelsDescription
flexfs_meta_sessionsGaugevolume_idActive client sessions per volume.

Database folder metrics

Section titled “Database folder metrics”
MetricTypeLabelsDescription
flexfs_meta_db_folder_disk_capacity_bytesGauge(none)Total capacity of the filesystem containing the database folder.

Database internals

Section titled “Database internals”
MetricTypeLabelsDescription
flexfs_meta_db_block_cache_hits_totalCounter(none)Block cache hits (shared across volumes).
flexfs_meta_db_block_cache_misses_totalCounter(none)Block cache misses (shared across volumes).
flexfs_meta_db_block_cache_size_bytesGauge(none)Block cache size in bytes (shared across volumes).
flexfs_meta_db_compaction_countCountervolume_idTotal compactions.
flexfs_meta_db_compaction_estimated_debt_bytesGaugevolume_idEstimated compaction debt in bytes.
flexfs_meta_db_disk_usage_bytesGaugevolume_idTotal disk space used.
flexfs_meta_db_flush_countCountervolume_idTotal flushes.
flexfs_meta_db_memtable_countGaugevolume_idNumber of memtables.
flexfs_meta_db_memtable_size_bytesGaugevolume_idMemtable size in bytes.
flexfs_meta_db_read_amplificationGaugevolume_idRead amplification.
flexfs_meta_db_table_itersGaugevolume_idOpen sstable iterators.
flexfs_meta_db_wal_bytes_in_totalCountervolume_idLogical bytes written to WAL.
flexfs_meta_db_wal_bytes_written_totalCountervolume_idPhysical bytes written to WAL.
flexfs_meta_db_wal_filesGaugevolume_idNumber of live WAL files.
flexfs_meta_db_wal_size_bytesGaugevolume_idSize of live WAL data in bytes.

Proxy server metrics

Section titled “Proxy server metrics”

Namespace: flexfs_proxy

REST metrics

Section titled “REST metrics”
MetricTypeLabelsDescription
flexfs_proxy_rest_ops_totalCountermethod, statusTotal REST operations by method and status.
flexfs_proxy_rest_duration_secondsHistogrammethodREST operation latency in seconds.

Histogram buckets (seconds): 0.0001, 0.00025, 0.0005, 0.001, 0.0025, 0.005, 0.01, 0.025, 0.05, 0.1, 0.25, 0.5, 1, 2.5, 5, 10

Cache metrics

Section titled “Cache metrics”
MetricTypeLabelsDescription
flexfs_proxy_cache_clean_blocksGauge(none)Number of clean cached blocks.
flexfs_proxy_cache_clean_bytesGauge(none)Total size of clean cached blocks in bytes.
flexfs_proxy_cache_dirty_blocksGauge(none)Number of dirty blocks pending writeback.
flexfs_proxy_cache_dirty_bytesGauge(none)Total size of dirty blocks in bytes.
flexfs_proxy_cache_disk_capacity_bytesGauge(none)Total capacity of the filesystem containing the cache folder.
flexfs_proxy_cache_disk_quota_bytesGauge(none)Configured disk quota in bytes.

Database folder metrics

Section titled “Database folder metrics”
MetricTypeLabelsDescription
flexfs_proxy_db_folder_disk_capacity_bytesGauge(none)Total capacity of the filesystem containing the database folder.

Database internals

Section titled “Database internals”
MetricTypeLabelsDescription
flexfs_proxy_db_block_cache_hits_totalCounter(none)Block cache hits.
flexfs_proxy_db_block_cache_misses_totalCounter(none)Block cache misses.
flexfs_proxy_db_block_cache_size_bytesGauge(none)Block cache size in bytes.
flexfs_proxy_db_compaction_countCounter(none)Total compactions.
flexfs_proxy_db_compaction_estimated_debt_bytesGauge(none)Estimated compaction debt in bytes.
flexfs_proxy_db_disk_usage_bytesGauge(none)Total disk space used by index.
flexfs_proxy_db_flush_countCounter(none)Total flushes.
flexfs_proxy_db_memtable_countGauge(none)Number of memtables.
flexfs_proxy_db_memtable_size_bytesGauge(none)Memtable size in bytes.
flexfs_proxy_db_read_amplificationGauge(none)Read amplification.
flexfs_proxy_db_table_itersGauge(none)Open sstable iterators.
flexfs_proxy_db_wal_bytes_in_totalCounter(none)Logical bytes written to WAL.
flexfs_proxy_db_wal_bytes_written_totalCounter(none)Physical bytes written to WAL.
flexfs_proxy_db_wal_filesGauge(none)Number of live WAL files.
flexfs_proxy_db_wal_size_bytesGauge(none)Size of live WAL data in bytes.

Standard Go and process metrics

Section titled “Standard Go and process metrics”

Both servers also expose the default Prometheus Go runtime and process collectors:

  • go_* metrics (goroutines, GC stats, memory allocation)
  • process_* metrics (CPU time, resident memory, file descriptors, start time)

Next steps

Section titled “Next steps”