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Key Monitoring Metrics of TiKV

If you use TiUP or TiDB Ansible to deploy the TiDB cluster, the monitoring system (Prometheus/Grafana) is deployed at the same time. For more information, see Overview of the Monitoring Framework.

The Grafana dashboard is divided into a series of sub dashboards which include Overview, PD, TiDB, TiKV, Node_exporter, and so on. A lot of metrics are there to help you diagnose.

You can get an overview of the component TiKV status from the TiKV-Details dashboard, where the key metrics are displayed. According to the Performance Map, you can check whether the status of the cluster is as expected.

This document provides a detailed description of these key metrics on the TiKV-Details dashboard.

Cluster

  • Store size: The storage size per TiKV instance
  • Available size: The available capacity per TiKV instance
  • Capacity size: The capacity size per TiKV instance
  • CPU: The CPU utilization per TiKV instance
  • Memory: The memory usage per TiKV instance
  • IO utilization: The I/O utilization per TiKV instance
  • MBps: The total bytes of read and write in each TiKV instance
  • QPS: The QPS per command in each TiKV instance
  • Errps: The rate of gRPC message failures
  • leader: The number of leaders per TiKV instance
  • Region: The number of Regions per TiKV instance
  • Uptime: The runtime of TiKV since last restart

TiKV Dashboard - Cluster metrics

Errors

  • Critical error: The number of critical errors
  • Server is busy: Indicates occurrences of events that make the TiKV instance unavailable temporarily, such as Write Stall, Channel Full, and so on. It should be 0 in normal case.
  • Server report failures: The number of error messages reported by server. It should be 0 in normal case.
  • Raftstore error: The number of Raftstore errors per type on each TiKV instance
  • Scheduler error: The number of scheduler errors per type on each TiKV instance
  • Coprocessor error: The number of coprocessor errors per type on each TiKV instance
  • gRPC message error: The number of gRPC message errors per type on each TiKV instance
  • Leader drop: The count of dropped leaders per TiKV instance
  • Leader missing: The count of missing leaders per TiKV instance

TiKV Dashboard - Errors metrics

Server

  • CF size: The size of each column family
  • Store size: The storage size per TiKV instance
  • Channel full: The number of Channel Full errors per TiKV instance. It should be 0 in normal case.
  • Active written leaders: The number of leaders being written on each TiKV instance
  • Approximate Region size: The approximate Region size
  • Approximate Region size Histogram: The histogram of each approximate Region size
  • Region average written keys: The average number of written keys to Regions per TiKV instance
  • Region average written bytes: The average written bytes to Regions per TiKV instance

TiKV Dashboard - Server metrics

gRPC

  • gRPC message count: The rate of gRPC messages per type
  • gRPC message failed: The rate of failed gRPC messages
  • 99% gRPC message duration: The gRPC message duration per message type (P99)
  • Average gRPC message duration: The average execution time of gRPC messages
  • gRPC batch size: The batch size of gRPC messages between TiDB and TiKV
  • Raft message batch size: The batch size of Raft messages between TiKV instances

Thread CPU

  • Raft store CPU: The CPU utilization of the raftstore thread. The CPU utilization should be less than 80% * raftstore.store-pool-size in normal case.
  • Async apply CPU: The CPU utilization of the async apply thread. The CPU utilization should be less than 90% * raftstore.apply-pool-size in normal cases.
  • Scheduler worker CPU: The CPU utilization of the scheduler worker thread. The CPU utilization should be less than 90% * storage.scheduler-worker-pool-size in normal cases.
  • gRPC poll CPU: The CPU utilization of the gRPC thread. The CPU utilization should be less than 80% * server.grpc-concurrency in normal cases.
  • Unified read pool CPU: The CPU utilization of the unified read pool thread
  • Storage ReadPool CPU: The CPU utilization of the storage read pool thread
  • Coprocessor CPU: The CPU utilization of the coprocessor thread
  • RocksDB CPU: The CPU utilization of the RocksDB thread
  • Split check CPU: The CPU utilization of the split check thread
  • GC worker CPU: The CPU utilization of the GC worker thread
  • Snapshot worker CPU: The CPU utilization of the snapshot worker thread

PD

  • PD requests: The rate at which TiKV sends to PD
  • PD request duration (average): The average duration of processing requests that TiKV sends to PD
  • PD heartbeats: The rate at which heartbeat messages are sent from TiKV to PD
  • PD validate peers: The rate at which messages are sent from TiKV to PD to validate TiKV peers

Raft IO

  • Apply log duration: The time consumed for Raft to apply logs
  • Apply log duration per server: The time consumed for Raft to apply logs per TiKV instance
  • Append log duration: The time consumed for Raft to append logs
  • Append log duration per server: The time consumed for Raft to append logs per TiKV instance
  • Commit log duration: The time consumed by Raft to commit logs
  • Commit log duration per server: The time consumed by Raft to commit logs per TiKV instance

TiKV Dashboard - Raft IO metrics

Raft process

  • Ready handled: The count of handled ready operations per second
  • 0.99 Duration of Raft store events: The time consumed by Raftstore events (P99)
  • Process ready duration: The time consumed for processes to be ready in Raft
  • Process ready duration per server: The time consumed for peer processes to be ready in Raft per TiKV instance. It should be less than 2 seconds (P99.99).

TiKV Dashboard - Raft process metrics

Raft message

  • Sent messages per server: The number of Raft messages sent by each TiKV instance per second
  • Flush messages per server: The number of Raft messages flushed by the Raft client in each TiKV instance per second
  • Receive messages per server: The number of Raft messages received by each TiKV instance per second
  • Messages: The number of Raft messages sent per type per second
  • Vote: The number of Vote messages sent in Raft per second
  • Raft dropped messages: The number of dropped Raft messages per type per second

TiKV Dashboard - Raft message metrics

Raft propose

  • Raft apply proposals per ready: The histogram of the number of proposals that each ready operation contains in a batch while applying proposal.
  • Raft read/write proposals: The number of proposals per type per second
  • Raft read proposals per server: The number of read proposals made by each TiKV instance per second
  • Raft write proposals per server: The number of write proposals made by each TiKV instance per second
  • Propose wait duration: The histogram of waiting time of each proposal
  • Propose wait duration per server: The histogram of waiting time of each proposal per TiKV instance
  • Apply wait duration: The histogram of apply time of each proposal
  • Apply wait duration per server: The histogram of apply time of each proposal per TiKV instance
  • Raft log speed: The average rate at which peers propose logs

TiKV Dashboard - Raft propose metrics

Raft admin

  • Admin proposals: The number of admin proposals per second
  • Admin apply: The number of processed apply commands per second
  • Check split: The number of Raftstore split check commands per second
  • 99.99% Check split duration: The time consumed when running split check commands (P99.99)

TiKV Dashboard - Raft admin metrics

Local reader

  • Local reader requests: The number of total requests and the number of rejections from the local read thread

TiKV Dashboard - Local reader metrics

Unified Read Pool

  • Time used by level: The time consumed for each level in the unified read pool. Level 0 means small queries.
  • Level 0 chance: The proportion of level 0 tasks in unified read pool
  • Running tasks: The number of tasks running concurrently in the unified read pool

Storage

  • Storage command total: The number of received command by type per second
  • Storage async request error: The number of engine asynchronous request errors per second
  • Storage async snapshot duration: The time consumed by processing asynchronous snapshot requests. It should be less than 1s in .99.
  • Storage async write duration: The time consumed by processing asynchronous write requests. It should be less than 1s in .99.

TiKV Dashboard - Storage metrics

Scheduler

  • Scheduler stage total: The number of commands at each stage per second. There should not be a lot of errors in a short time.
  • Scheduler writing bytes: The total written bytes by commands processed on each TiKV instance
  • Scheduler priority commands: The count of different priority commands per second
  • Scheduler pending commands: The count of pending commands per TiKV instance per second

TiKV Dashboard - Scheduler metrics

Scheduler - commit

  • Scheduler stage total: The number of commands at each stage per second when executing the commit command. There should not be a lot of errors in a short time.
  • Scheduler command duration: The time consumed when executing the commit command. It should be less than 1s.
  • Scheduler latch wait duration: The waiting time caused by latch when executing the commit command. It should be less than 1s.
  • Scheduler keys read: The count of keys read by a commit command
  • Scheduler keys written: The count of keys written by a commit command
  • Scheduler scan details: The keys scan details of each CF when executing the commit command.
  • Scheduler scan details [lock]: The keys scan details of lock CF when executing the commit command
  • Scheduler scan details [write]: The keys scan details of write CF when executing the commit command
  • Scheduler scan details [default]: The keys scan details of default CF when executing the commit command

TiKV Dashboard - Scheduler commit metrics

Scheduler - pessimistic_rollback

  • Scheduler stage total: The number of commands at each stage per second when executing the pessimistic_rollback command. There should not be a lot of errors in a short time.
  • Scheduler command duration: The time consumed when executing the pessimistic_rollback command. It should be less than 1s.
  • Scheduler latch wait duration: The waiting time caused by latch when executing the pessimistic_rollback command. It should be less than 1s.
  • Scheduler keys read: The count of keys read by a pessimistic_rollback command
  • Scheduler keys written: The count of keys written by a pessimistic_rollback command
  • Scheduler scan details: The keys scan details of each CF when executing the pessimistic_rollback command.
  • Scheduler scan details [lock]: The keys scan details of lock CF when executing the pessimistic_rollback command
  • Scheduler scan details [write]: The keys scan details of write CF when executing the pessimistic_rollback command
  • Scheduler scan details [default]: The keys scan details of default CF when executing the pessimistic_rollback command

Scheduler - prewrite

  • Scheduler stage total: The number of commands at each stage per second when executing the prewrite command. There should not be a lot of errors in a short time.
  • Scheduler command duration: The time consumed when executing the prewrite command. It should be less than 1s.
  • Scheduler latch wait duration: The waiting time caused by latch when executing the prewrite command. It should be less than 1s.
  • Scheduler keys read: The count of keys read by a prewrite command
  • Scheduler keys written: The count of keys written by a prewrite command
  • Scheduler scan details: The keys scan details of each CF when executing the prewrite command.
  • Scheduler scan details [lock]: The keys scan details of lock CF when executing the prewrite command
  • Scheduler scan details [write]: The keys scan details of write CF when executing the prewrite command
  • Scheduler scan details [default]: The keys scan details of default CF when executing the prewrite command

Scheduler - rollback

  • Scheduler stage total: The number of commands at each stage per second when executing the rollback command. There should not be a lot of errors in a short time.
  • Scheduler command duration: The time consumed when executing the rollback command. It should be less than 1s.
  • Scheduler latch wait duration: The waiting time caused by latch when executing the rollback command. It should be less than 1s.
  • Scheduler keys read: The count of keys read by a rollback command
  • Scheduler keys written: The count of keys written by a rollback command
  • Scheduler scan details: The keys scan details of each CF when executing the rollback command.
  • Scheduler scan details [lock]: The keys scan details of lock CF when executing the rollback command
  • Scheduler scan details [write]: The keys scan details of write CF when executing the rollback command
  • Scheduler scan details [default]: The keys scan details of default CF when executing the rollback command

GC

  • MVCC versions: The number of versions for each key
  • MVCC delete versions: The number of versions deleted by GC for each key
  • GC tasks: The count of GC tasks processed by gc_worker
  • GC tasks Duration: The time consumed when executing GC tasks
  • GC keys (write CF): The count of keys in write CF affected during GC
  • TiDB GC worker actions: The count of TiDB GC worker actions
  • TiDB GC seconds: The GC duration
  • GC speed: The number of keys deleted by GC per second
  • TiKV AutoGC Working: The status of Auto GC
  • ResolveLocks Progress: The progress of the first phase of GC (Resolve Locks)
  • TiKV Auto GC Progress: The progress of the second phase of GC
  • TiKV Auto GC SafePoint: The value of TiKV GC safe point. The safe point is the current GC timestamp
  • GC lifetime: The lifetime of TiDB GC
  • GC interval: The interval of TiDB GC

Snapshot

  • Rate snapshot message: The rate at which Raft snapshot messages are sent
  • 99% Handle snapshot duration: The time consumed to handle snapshots (P99)
  • Snapshot state count: The number of snapshots per state
  • 99.99% Snapshot size: The snapshot size (P99.99)
  • 99.99% Snapshot KV count: The number of KV within a snapshot (P99.99)

Task

  • Worker handled tasks: The number of tasks handled by worker per second
  • Worker pending tasks: Current number of pending and running tasks of worker per second. It should be less than 1000 in normal case.
  • FuturePool handled tasks: The number of tasks handled by future pool per second
  • FuturePool pending tasks: Current number of pending and running tasks of future pool per second

Coprocessor Overview

  • Request duration: The total duration from the time of receiving the coprocessor request to the time of finishing processing the request
  • Total Requests: The number of requests by type per second
  • Handle duration: The histogram of time spent actually processing coprocessor requests per minute
  • Total Request Errors: The number of request errors of Coprocessor per second. There should not be a lot of errors in a short time.
  • Total KV Cursor Operations: The total number of the KV cursor operations by type per second, such as select, index, analyze_table, analyze_index, checksum_table, checksum_index, and so on.
  • KV Cursor Operations: The histogram of KV cursor operations by type per second
  • Total RocksDB Perf Statistics: The statistics of RocksDB performance
  • Total Response Size: The total size of coprocessor response

Coprocessor Detail

  • Handle duration: The histogram of time spent actually processing coprocessor requests per minute
  • 95% Handle duration by store: The time consumed to handle coprocessor requests per TiKV instance per second (P95)
  • Wait duration: The time consumed when coprocessor requests are waiting to be handled. It should be less than 10s (P99.99).
  • 95% Wait duration by store: The time consumed when coprocessor requests are waiting to be handled per TiKV instance per second (P95)
  • Total DAG Requests: The total number of DAG requests per second
  • Total DAG Executors: The total number of DAG executors per second
  • Total Ops Details (Table Scan): The number of RocksDB internal operations per second when executing select scan in coprocessor
  • Total Ops Details (Index Scan): The number of RocksDB internal operations per second when executing index scan in coprocessor
  • Total Ops Details by CF (Table Scan): The number of RocksDB internal operations for each CF per second when executing select scan in coprocessor
  • Total Ops Details by CF (Index Scan): The number of RocksDB internal operations for each CF per second when executing index scan in coprocessor

Threads

  • Threads state: The state of TiKV threads
  • Threads IO: The I/O traffic of each TiKV thread
  • Thread Voluntary Context Switches: The number of TiKV threads voluntary context switches
  • Thread Nonvoluntary Context Switches: The number of TiKV threads nonvoluntary context switches

RocksDB - kv/raft

  • Get operations: The count of get operations per second
  • Get duration: The time consumed when executing get operations
  • Seek operations: The count of seek operations per second
  • Seek duration: The time consumed when executing seek operations
  • Write operations: The count of write operations per second
  • Write duration: The time consumed when executing write operations
  • WAL sync operations: The count of WAL sync operations per second
  • Write WAL duration: The time consumed for writing WAL
  • WAL sync duration: The time consumed when executing WAL sync operations
  • Compaction operations: The count of compaction and flush operations per second
  • Compaction duration: The time consumed when executing the compaction and flush operations
  • SST read duration: The time consumed when reading SST files
  • Write stall duration: Write stall duration. It should be 0 in normal case.
  • Memtable size: The memtable size of each column family
  • Memtable hit: The hit rate of memtable
  • Block cache size: The block cache size. Broken down by column family if shared block cache is disabled.
  • Block cache hit: The hit rate of block cache
  • Block cache flow: The flow rate of block cache operations per type
  • Block cache operations: The count of block cache operations per type
  • Keys flow: The flow rate of operations on keys per type
  • Total keys: The count of keys in each column family
  • Read flow: The flow rate of read operations per type
  • Bytes / Read: The bytes per read operation
  • Write flow: The flow rate of write operations per type
  • Bytes / Write: The bytes per write operation
  • Compaction flow: The flow rate of compaction operations per type
  • Compaction pending bytes: The pending bytes to be compacted
  • Read amplification: The read amplification per TiKV instance
  • Compression ratio: The compression ratio of each level
  • Number of snapshots: The number of snapshots per TiKV instance
  • Oldest snapshots duration: The time that the oldest unreleased snapshot survivals
  • Number files at each level: The number of SST files for different column families in each level
  • Ingest SST duration seconds: The time consumed to ingest SST files
  • Stall conditions changed of each CF: Stall conditions changed of each column family

Titan - All

  • Blob file count: The number of Titan blob files
  • Blob file size: The total size of Titan blob file
  • Live blob size: The total size of valid blob record
  • Blob cache hit: The hit rate of Titan block cache
  • Iter touched blob file count: The number of blob file involved in a single iterator
  • Blob file discardable ratio distribution: The ratio distribution of blob record failure of blob files
  • Blob key size: The size of Titan blob keys
  • Blob value size: The size of Titan blob values
  • Blob get operations: The count of get operations in Titan blob
  • Blob get duration: The time consumed when executing get operations in Titan blob
  • Blob iter operations: The time consumed when executing iter operations in Titan blob
  • Blob seek duration: The time consumed when executing seek operations in Titan blob
  • Blob next duration: The time consumed when executing next operations in Titan blob
  • Blob prev duration: The time consumed when executing prev operations in Titan blob
  • Blob keys flow: The flow rate of operations on Titan blob keys
  • Blob bytes flow: The flow rate of bytes on Titan blob keys
  • Blob file read duration: The time consumed when reading Titan blob file
  • Blob file write duration: The time consumed when writing Titan blob file
  • Blob file sync operations: The count of blob file sync operations
  • Blob file sync duration: The time consumed when synchronizing blob file
  • Blob GC action: The count of Titan GC actions
  • Blob GC duration: The Titan GC duration
  • Blob GC keys flow: The flow rate of keys read and written by Titan GC
  • Blob GC bytes flow: The flow rate of bytes read and written by Titan GC
  • Blob GC input file size: The size of Titan GC input file
  • Blob GC output file size: The size of Titan GC output file
  • Blob GC file count: The count of blob files involved in Titan GC

Lock manager

  • Thread CPU: The CPU utilization of the lock manager thread
  • Handled tasks: The number of tasks handled by lock manager
  • Waiter lifetime duration: The waiting time of the transaction for the lock to be released
  • Wait table: The status information of wait table, including the number of locks and the number of transactions waiting for the lock
  • Deadlock detect duration: The time consumed for detecting deadlock
  • Detect error: The number of errors encountered when detecting deadlock, including the number of deadlocks
  • Deadlock detector leader: The information of the node where the deadlock detector leader is located

Memory

  • Allocator Stats: The statistics of the memory allocator

Backup

  • Backup CPU: The CPU utilization of the backup thread
  • Range Size: The histogram of backup range size
  • Backup Duration: The time consumed for backup
  • Backup Flow: The total bytes of backup
  • Disk Throughput: The disk throughput per instance
  • Backup Range Duration: The time consumed for backing up a range
  • Backup Errors: The number of errors encountered during a backup

Encryption

  • Encryption data keys: The total number of encrypted data keys
  • Encrypted files: The number of encrypted files
  • Encryption initialized: Shows whether encryption is enabled. 1 means enabled.
  • Encryption meta files size: The size of the encryption meta file
  • Encrypt/decrypt data nanos: The histogram of duration on encrypting/decrypting data each time
  • Read/write encryption meta duration: The time consumed for reading/writing encryption meta files

Explanation of Common Parameters

gRPC Message Type

  1. Transactional API:

    • kv_get: The command of getting the latest version of data specified by ts
    • kv_scan: The command of scanning a range of data
    • kv_prewrite: The command of prewriting the data to be committed at first phase of 2PC
    • kv_pessimistic_lock: The command of adding a pessimistic lock to the key to prevent other transaction from modifying this key
    • kv_pessimistic_rollback: The command of deleting the pessimistic lock on the key
    • kv_txn_heart_beat: The command of updating lock_ttl for pessimistic transactions or large transactions to prevent them from rolling back
    • kv_check_txn_status: The command of checking the status of the transaction
    • kv_commit: The command of committing the data written by the prewrite command
    • kv_cleanup: The command of rolling back a transaction, which is deprecated in v4.0
    • kv_batch_get: The command of getting the value of batch key at once, similar to kv_get
    • kv_batch_rollback: The command of batch rollback of multiple prewrite transactions
    • kv_scan_lock: The command of scanning all locks with a version number before max_version to clean up expired transactions
    • kv_resolve_lock: The command of committing or rollback the transaction lock, according to the transaction status.
    • kv_gc: The command of GC
    • kv_delete_range: The command of deleting a range of data from TiKV

  2. Raw API:

    • raw_get: The command of getting the value of key
    • raw_batch_get: The command of getting the value of batch keys
    • raw_scan: The command of scanning a range of data
    • raw_batch_scan: The command of scanning multiple consecutive data range
    • raw_put: The command of writing a key/value pair
    • raw_batch_put: The command of writing a batch of key/value pairs
    • raw_delete: The command of deleting a key/value pair
    • raw_batch_delete: The command of a batch of key/value pairs
    • raw_delete_range: The command of deleting a range of data
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