TiDB-Binlog Monitoring Metrics and Alert Rules

This document describes TiDB-Binlog monitoring metrics in Grafana and explains the alert rules.

Monitoring metrics

TiDB-Binlog consists of two components: Pump and Drainer. This section shows the monitoring metrics of Pump and Drainer.

Pump monitoring metrics

To understand the Pump monitoring metrics, check the following table:

Pump monitoring metrics Description
Storage Size Records the total disk space (capacity) and the available disk space (available)
Metadata Records the biggest TSO (gc_tso) of the binlog that each Pump node can delete, and the biggest commit TSO (max_commit_tso) of the saved binlog
Write Binlog QPS by Instance Shows QPS of writing binlog requests received by each Pump node
Write Binlog Latency Records the latency time of each Pump node writing binlog
Storage Write Binlog Size Shows the size of the binlog data written by Pump
Storage Write Binlog Latency Records the latency time of the Pump storage module writing binlog
Pump Storage Error By Type Records the number of errors encountered by Pump, counted based on the type of error
Query TiKV The number of times that Pump queries the transaction status through TiKV

Drainer monitoring metrics

To understand the Drainer monitoring metrics, check the following table:

Drainer monitoring metrics Description
Checkpoint TSO Shows the biggest TSO time of the binlog that Drainer has already replicated into the downstream. You can get the lag by using the current time to subtract the binlog timestamp. But be noted that the timestamp is allocated by PD of the master cluster and is determined by the time of PD.
Pump Handle TSO Records the biggest TSO time among the binlog files that Drainer obtains from each Pump node
Pull Binlog QPS by Pump NodeID Shows the QPS when Drainer obtains binlog from each Pump node
95% Binlog Reach Duration By Pump Records the delay from the time when binlog is written into Pump to the time when the binlog is obtained by Drainer
Error By Type Shows the number of errors encountered by Drainer, counted based on the type of error
Drainer Event Shows the number of various types of events, including “ddl”, “insert”, “delete”, “update”, “flush”, and “savepoint”
Execute Time Records the time it takes to execute the SQL statement in the downstream, or the time it takes to write data into downstream
95% Binlog Size Shows the size of the binlog data that Drainer obtains from each Pump node
DDL Job Count Records the number of DDL statements handled by Drainer

Alert rules

Currently, TiDB-Binlog monitoring metrics are divided into the following three types based on the level of importance:

Emergency

binlog_pump_storage_error_count

  • Description: Pump fails to write the binlog data to the local storage
  • Monitoring rule: changes(binlog_pump_storage_error_count[1m]) > 0
  • Solution: Check whether an error exists in the pump_storage_error monitoring and check the Pump log to find the causes

Critical

binlog_drainer_checkpoint_high_delay

  • Description: The delay of Drainer replication exceeds one hour

  • Monitoring rule: (time() - binlog_drainer_checkpoint_tso / 1000) > 3600

  • Solutions:

    • Check whether it is too slow to obtain the data from Pump:

      You can check handle tso of Pump to get the time for the latest message of each Pump. Check whether a high latency exists for Pump and make sure the corresponding Pump is running normally

    • Check whether it is too slow to replicate data in the downstream based on Drainer event and Drainer execute latency:

      • If Drainer execute time is too large, check the network bandwidth and latency between the machine with Drainer deployed and the machine with the target database deployed, and the state of the target database
      • If Drainer execute time is not too large and Drainer event is too small, add work count and batch and retry
    • If the two solutions above cannot work, contact support@pingcap.com

Warning

binlog_pump_write_binlog_rpc_duration_seconds_bucket

  • Description: It takes too much time for Pump to handle the TiDB request of writing binlog

  • Monitoring rule: histogram_quantile(0.9, rate(binlog_pump_rpc_duration_seconds_bucket{method="WriteBinlog"}[5m])) > 1

  • Solution:

    • Verify the disk performance pressure and check the disk performance monitoring via node exported
    • If both disk latency and util are low, contact support@pingcap.com

binlog_pump_storage_write_binlog_duration_time_bucket

  • Description: The time it takes for Pump to write the local binlog to the local disk
  • Monitoring rule: histogram_quantile(0.9, rate(binlog_pump_storage_write_binlog_duration_time_bucket{type="batch"}[5m])) > 1
  • Solution: Check the state of the local disk of Pump and fix the problem

binlog_pump_storage_available_size_less_than_20G

  • Description: The available disk space of Pump is less than 20G
  • Monitoring rule: binlog_pump_storage_storage_size_bytes{type="available"} < 20 * 1024 * 1024 * 1024
  • Solution: Check whether Pump gc_tso is normal. If not, adjust the GC time configuration of Pump or get the corresponding Pump offline

binlog_drainer_checkpoint_tso_no_change_for_1m

  • Description: Drainer checkpoint has not been updated for one minute
  • Monitoring rule: changes(binlog_drainer_checkpoint_tso[1m]) < 1
  • Solution: Check whether all the Pumps that are not offline are running normally

binlog_drainer_execute_duration_time_more_than_10s

  • Description: The transaction time it takes Drainer to replicate data to TiDB. If it is too large, the Drainer replication of data is affected

  • Monitoring rule: histogram_quantile(0.9, rate(binlog_drainer_execute_duration_time_bucket[1m])) > 10

  • Solutions:

    • Check the TiDB cluster state
    • Check the Drainer log or monitor. If a DDL operation causes this problem, you can ignore it