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”| Metric | Type | Labels | Description |
|---|---|---|---|
| flexfs_meta_rpc_ops_total | Counter | volume_id, method, status | Total RPC operations by method and status. |
| flexfs_meta_rpc_duration_seconds | Histogram | volume_id, method | RPC 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”| Metric | Type | Labels | Description |
|---|---|---|---|
| flexfs_meta_volume_info | Gauge | volume_id, volume_name | Volume metadata. Always 1 per volume; use labels to map IDs to names. |
Volume gauge metrics
Section titled “Volume gauge metrics”| Metric | Type | Labels | Description |
|---|---|---|---|
| flexfs_meta_volume_blocks | Gauge | volume_id | Number of active blocks. |
| flexfs_meta_volume_blocks_retired | Gauge | volume_id | Number of retired blocks. |
| flexfs_meta_volume_dentries | Gauge | volume_id | Number of directory entries. |
| flexfs_meta_volume_inodes | Gauge | volume_id | Number of inodes. |
| flexfs_meta_volume_size_bytes | Gauge | volume_id | Total volume size in bytes. |
Volume I/O counters
Section titled “Volume I/O counters”| Metric | Type | Labels | Description |
|---|---|---|---|
| flexfs_meta_volume_blocks_read_total | Counter | volume_id | Total blocks read. |
| flexfs_meta_volume_blocks_written_total | Counter | volume_id | Total blocks written. |
| flexfs_meta_volume_bytes_read_total | Counter | volume_id | Total bytes read at FUSE boundary. |
| flexfs_meta_volume_bytes_written_total | Counter | volume_id | Total bytes written at FUSE boundary. |
Session metrics
Section titled “Session metrics”| Metric | Type | Labels | Description |
|---|---|---|---|
| flexfs_meta_sessions | Gauge | volume_id | Active client sessions per volume. |
Database folder metrics
Section titled “Database folder metrics”| Metric | Type | Labels | Description |
|---|---|---|---|
| flexfs_meta_db_folder_disk_capacity_bytes | Gauge | (none) | Total capacity of the filesystem containing the database folder. |
Database internals
Section titled “Database internals”| Metric | Type | Labels | Description |
|---|---|---|---|
| flexfs_meta_db_block_cache_hits_total | Counter | (none) | Block cache hits (shared across volumes). |
| flexfs_meta_db_block_cache_misses_total | Counter | (none) | Block cache misses (shared across volumes). |
| flexfs_meta_db_block_cache_size_bytes | Gauge | (none) | Block cache size in bytes (shared across volumes). |
| flexfs_meta_db_compaction_count | Counter | volume_id | Total compactions. |
| flexfs_meta_db_compaction_estimated_debt_bytes | Gauge | volume_id | Estimated compaction debt in bytes. |
| flexfs_meta_db_disk_usage_bytes | Gauge | volume_id | Total disk space used. |
| flexfs_meta_db_flush_count | Counter | volume_id | Total flushes. |
| flexfs_meta_db_memtable_count | Gauge | volume_id | Number of memtables. |
| flexfs_meta_db_memtable_size_bytes | Gauge | volume_id | Memtable size in bytes. |
| flexfs_meta_db_read_amplification | Gauge | volume_id | Read amplification. |
| flexfs_meta_db_table_iters | Gauge | volume_id | Open sstable iterators. |
| flexfs_meta_db_wal_bytes_in_total | Counter | volume_id | Logical bytes written to WAL. |
| flexfs_meta_db_wal_bytes_written_total | Counter | volume_id | Physical bytes written to WAL. |
| flexfs_meta_db_wal_files | Gauge | volume_id | Number of live WAL files. |
| flexfs_meta_db_wal_size_bytes | Gauge | volume_id | Size of live WAL data in bytes. |
Proxy server metrics
Section titled “Proxy server metrics”Namespace: flexfs_proxy
REST metrics
Section titled “REST metrics”| Metric | Type | Labels | Description |
|---|---|---|---|
| flexfs_proxy_rest_ops_total | Counter | method, status | Total REST operations by method and status. |
| flexfs_proxy_rest_duration_seconds | Histogram | method | REST 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”| Metric | Type | Labels | Description |
|---|---|---|---|
| flexfs_proxy_cache_clean_blocks | Gauge | (none) | Number of clean cached blocks. |
| flexfs_proxy_cache_clean_bytes | Gauge | (none) | Total size of clean cached blocks in bytes. |
| flexfs_proxy_cache_dirty_blocks | Gauge | (none) | Number of dirty blocks pending writeback. |
| flexfs_proxy_cache_dirty_bytes | Gauge | (none) | Total size of dirty blocks in bytes. |
| flexfs_proxy_cache_disk_capacity_bytes | Gauge | (none) | Total capacity of the filesystem containing the cache folder. |
| flexfs_proxy_cache_disk_quota_bytes | Gauge | (none) | Configured disk quota in bytes. |
Database folder metrics
Section titled “Database folder metrics”| Metric | Type | Labels | Description |
|---|---|---|---|
| flexfs_proxy_db_folder_disk_capacity_bytes | Gauge | (none) | Total capacity of the filesystem containing the database folder. |
Database internals
Section titled “Database internals”| Metric | Type | Labels | Description |
|---|---|---|---|
| flexfs_proxy_db_block_cache_hits_total | Counter | (none) | Block cache hits. |
| flexfs_proxy_db_block_cache_misses_total | Counter | (none) | Block cache misses. |
| flexfs_proxy_db_block_cache_size_bytes | Gauge | (none) | Block cache size in bytes. |
| flexfs_proxy_db_compaction_count | Counter | (none) | Total compactions. |
| flexfs_proxy_db_compaction_estimated_debt_bytes | Gauge | (none) | Estimated compaction debt in bytes. |
| flexfs_proxy_db_disk_usage_bytes | Gauge | (none) | Total disk space used by index. |
| flexfs_proxy_db_flush_count | Counter | (none) | Total flushes. |
| flexfs_proxy_db_memtable_count | Gauge | (none) | Number of memtables. |
| flexfs_proxy_db_memtable_size_bytes | Gauge | (none) | Memtable size in bytes. |
| flexfs_proxy_db_read_amplification | Gauge | (none) | Read amplification. |
| flexfs_proxy_db_table_iters | Gauge | (none) | Open sstable iterators. |
| flexfs_proxy_db_wal_bytes_in_total | Counter | (none) | Logical bytes written to WAL. |
| flexfs_proxy_db_wal_bytes_written_total | Counter | (none) | Physical bytes written to WAL. |
| flexfs_proxy_db_wal_files | Gauge | (none) | Number of live WAL files. |
| flexfs_proxy_db_wal_size_bytes | Gauge | (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”- Prometheus setup — scrape configuration
- Grafana dashboards — visualization
- Alerting — alert rules based on these metrics