CM Server Parameters

log_dir

Parameter description: Specifies the directory where CM Server logs are stored. The value can be an absolute path, or a path relative to the CM Server data directory.

Value range: a string. The modification takes effect after CM Server is restarted. For details about how to modify this parameter, see Table 2.

Default value: "log", indicating that CM Server logs are generated in the CM Server data directory.

log_file_size

Parameter description: Specifies the size of a log file. If a log file exceeds the specified size, a new one is created to record log information.

Value range: an integer ranging from 0 to 2047. The unit is MB. The modification of this parameter takes effect after reloading. For details about how to modify the parameter, see Table 2.

Default value: 16MB

log_min_messages

Parameter description: Specifies which message levels are written to the CM Server log. Each level covers all the levels following it. The lower the level is, the fewer messages will be written into the log.

Value range: enumerated type. Valid values are debug5, debug1, log, warning, error, and fatal. The modification of this parameter takes effect after reloading. For details about how to modify the parameter, see Table 2.

Default value: warning

thread_count

Parameter description: Specifies the number of threads in the agent thread pool.

Parameter type: string

Unit: none

Value range: This parameter consists of two parts: 'worker_thread_count and io_ratio. The meanings of the two parts are as follows:

• worker_thread_count: specifies the number of AgentWorker threads. The value ranges from 2 to 1000.
• io_ratio: specifies the ratio of I/O threads to worker threads. The value n indicates that one AgentIO thread corresponds to n AgentWorker threads. The value ranges from 1 to 100. At least one AgentIO thread is required.

Default value: "(1000,1)"

Setting method: Refer to the set cm parameters table in "Unified Database Management Tool > cm_ctl Tool Introduction" in Tool Reference. Then run the reload command for the settings to take effect.

Setting suggestion: Retain the default value. If you want to adjust the value, make sure you understand the parameter meaning and adjust the value with caution to avoid risks caused by misoperations.

alarm_component

Parameter description: Specifies the location of the alarm component that processes alarms.

Value range: a string. The modification of this parameter takes effect after reloading. For details about how to modify the parameter, see Table 2.

• If --alarm-type in the gs_preinstall script is set to 5, no third-party component is connected and alarms are written into system_alarm logs. In this case, the value of alarm_component is /opt/huawei/snas/bin/snas_cm_cmd.
• If --alarm-type in the gs_preinstall script is set to 1, a third-party component is connected. In this case, the value of alarm_component is the absolute path of the executable program of the third-party component.

Default value: /opt/huawei/snas/bin/snas_cm_cmd

instance_failover_delay_timeout

Parameter description: Specifies the delay in CM Server failover after the primary CM Server breakdown is detected.

Value range: an integer. The unit is s. The modification of this parameter takes effect after reloading. For details about how to modify the parameter, see Table 2.

Default value: 0

instance_heartbeat_timeout

Parameter description: Specifies the time to wait before the instance heartbeat times out.

Value range: an integer. The unit is s. The modification of this parameter takes effect after reloading. For details about how to modify the parameter, see Table 2.

Default value: 6

cmserver_ha_connect_timeout

Parameter description: Specifies the time to wait before the connection between the primary and standby CM Servers times out.

Value range: an integer. The unit is s. The modification of this parameter takes effect after reloading. For details about how to modify the parameter, see Table 2.

Default value: 2

cmserver_ha_heartbeat_timeout

Parameter description: Specifies the time to wait before the heartbeat between the primary and standby CM Servers times out.

Value range: an integer. The unit is s. The modification of this parameter takes effect after reloading. For details about how to modify the parameter, see Table 2.

Default value: 6

phony_dead_effective_time

Parameter description: Specifies the maximum number of times DN processes are detected as zombie. If the number of times a process is detected as zombie is greater than the specified value, the process is considered to be a zombie process and will be restarted.

Value range: an integer. The modification of this parameter takes effect after reloading. For details about how to modify the parameter, see Table 2.

Default value: 5

enable_transaction_read_only

Parameter description: Specifies whether the database is in read-only mode.

Value range: Boolean values on, off, true, false, yes, no, 1, and 0. The modification of this parameter takes effect after reloading. For details about how to modify the parameter, see Table 2.

Default value: on

datastorage_threshold_check_interval

Parameter description: Specifies the interval for checking the disk usage. The system checks the disk usage at the interval specified by the user.

Value range: an integer. The unit is s. The modification of this parameter takes effect after reloading. For details about how to modify the parameter, see Table 2.

Default value: 10

datastorage_threshold_value_check

Parameter description: Specifies the usage threshold of a read-only disk in a database. When the disk usage of the data directory exceeds the specified value, the database is automatically set to read-only mode. In the read-only mode, log replay cannot be restricted. Pay attention to the cluster disk capacity and handle read-only alarms in a timely manner to prevent the disk space from being used up; otherwise, the database cannot be quickly restored.

Parameter type: integer

Unit: percentage

Value range: 1 to 99.

Default value: 85

Setting method: The modification of this parameter takes effect after reloading. For details about how to modify the parameter, see Table 2.

Setting suggestion: Retain the default value. You can adjust this parameter based on the disk space. When adjusting this parameter, you are advised to adjust the max_size_for_xlog_retention parameter of the DN at the same time to prevent the instance read-only threshold from being triggered by backup operations.

max_datastorage_threshold_check

Parameter description: Specifies the maximum interval for checking the disk usage. After you modify the read-only mode parameter, the system automatically checks whether the disk usage reaches the threshold at the specified interval.

Value range: an integer. The unit is s. The modification of this parameter takes effect after reloading. For details about how to modify the parameter, see Table 2.

Default value: 43200

cmserver_ha_status_interval

Parameter description: Specifies the interval between synchronizations of primary and standby CM Server status.

Value range: an integer. The unit is s. The modification of this parameter takes effect after reloading. For details about how to modify the parameter, see Table 2.

Default value: 1

cmserver_self_vote_timeout

Parameter description: Specifies the time to wait before the CM Server self-voting times out.

Value range: an integer. The unit is s. The modification of this parameter takes effect after reloading. For details about how to modify the parameter, see Table 2.

Default value: 6

alarm_report_interval

Parameter description: Specifies the interval at which an alarm is reported.

Value range: a non-negative integer. The unit is s. The modification of this parameter takes effect after reloading. For details about how to modify the parameter, see Table 2.

Default value: 3

alarm_report_max_count

Parameter description: Specifies the maximum number of times an alarm is reported.

Value range: a non-negative integer. The modification of this parameter takes effect after reloading. For details about how to modify the parameter, see Table 2.

Default value: 1

enable_az_auto_switchover

Parameter description: Specifies whether to enable automatic AZ switchover. If this parameter is enabled, CM Server automatically switches over services among AZs. Otherwise, when a DN is faulty, services will not be automatically switched to another AZ even if the current AZ is unavailable. You can run the switchover command to manually switch services to another AZ.

Value range: a non-negative integer. 0: disabled; 1: enabled. The modification of this parameter takes effect after reloading. For details about how to modify the parameter, see Table 2.

Default value: 1

instance_keep_heartbeat_timeout

Parameter description: The CM Agent periodically checks the instance status and reports the status to the CM Server. If the instance status cannot be detected for a long time and the accumulated number of times exceeds the value of this parameter, the CM Server delivers a command to the CM Agent to restart the instance.

Value range: an integer. The unit is s. The modification of this parameter takes effect after reloading. For details about how to modify the parameter, see Table 2.

Default value: 40

az_switchover_threshold

Parameter description: If the failure rate of a DN shard in an AZ (Number of faulty DN shards/Total number of DN shards x 100%) exceeds the specified value, automatic AZ switchover is triggered.

Value range: an integer ranging from 0 to 100. The modification of this parameter takes effect after reloading. For details about how to modify the parameter, see Table 2.

Default value: 100

az_check_and_arbitrate_interval

Parameter description: Specifies the interval for checking the AZ status. If an AZ is abnormal, automatic AZ switchover is triggered.

Value range: an integer. The unit is s. The modification of this parameter takes effect after reloading. For details about how to modify the parameter, see Table 2.

Default value: 2

az_connect_check_interval

Parameter description: Specifies the interval at which the network connection between AZs is checked.

Value range: an integer. The unit is s. The modification of this parameter takes effect after reloading. For details about how to modify the parameter, see Table 2.

Default value: 60

az_connect_check_delay_time

Parameter description: Specifies the delay between two retries to check the network connection between AZs.

Value range: an integer. The unit is s. The modification of this parameter takes effect after reloading. For details about how to modify the parameter, see Table 2.

Default value: 150

cmserver_demote_delay_on_etcd_fault

Parameter description: Specifies the interval at which CM Server switches from the primary state to the standby state due to unhealthy ETCD.

Value range: an integer. The unit is s. The modification of this parameter takes effect after reloading. For details about how to modify the parameter, see Table 2.

Default value: 8

instance_phony_dead_restart_interval

Parameter description: Specifies the interval at which the CM Agent process restarts and kills a zombie DN. The interval between two consecutive kill operations cannot be less than the value of this parameter. Otherwise, the CM Agent process does not deliver commands.

Value range: an integer. The unit is s. The minimum value that takes effect is 1800. If this parameter is set to a value less than 1800, the value 1800 takes effect. The modification of this parameter takes effect after reloading. For details about how to modify the parameter, see Table 2.

Default value: 21600

cm_auth_method

Parameter description: Specifies the port authentication mode of the CM. trust indicates that port authentication is not configured. gss indicates that Kerberos port authentication is used. Note that you can change the value to gss only after the Kerberos server and client are successfully installed. Otherwise, the CM cannot communicate properly, affecting the database status.

Value range: gss or trust. The modification of this parameter takes effect after reloading. For details about how to modify the parameter, see Table 2.

Default value: trust

cm_krb_server_keyfile

Parameter description: Specifies the location of the key file on the Kerberos server. The value must be an absolute path. The file is usually stored in the ${GAUSSHOME}/kerberos directory and ends with keytab. The file name is the same as the name of the user who runs the database. This parameter is used together with cm_auth_method. If the cm_auth_method parameter is changed to gss, cm_krb_server_keyfile must also be configured as the correct path. Otherwise, the database status will be affected.

Value range: a string. The modification of this parameter takes effect after reloading. For details about how to modify the parameter, see Table 2.

Default value: ${GAUSSHOME}/kerberos/{UserName}.keytab. The default value cannot take effect and is used only as a prompt.

cm_server_arbitrate_delay_base_time_out

Parameter description: Specifies the basic delay duration for CM Server arbitration. If the primary CM Server is disconnected, the arbitration starts to be timed. If the disconnection duration exceeds the arbitration delay duration, a new primary CM Server will be selected. The arbitration delay duration is determined by the basic delay duration, the node index (server ID), and the incremental delay duration. The formula is as follows: Arbitration delay duration = Basic delay duration + Node index x Incremental delay duration

Value range: an integer. The unit is s. The index should be larger than 0. The modification of this parameter takes effect after reloading. For details about how to modify the parameter, see Table 2.

Default value: 10

cm_server_arbitrate_delay_incrememtal_time_out

Parameter description: Specifies the incremental delay duration for CM Server arbitration. If the primary CM Server is disconnected, the arbitration starts to be timed. If the disconnection duration exceeds the arbitration delay duration, a new primary CM Server will be selected. The arbitration delay duration is determined by the basic delay duration, the node index (server ID), and the incremental delay duration. The formula is as follows: Arbitration delay duration = Basic delay duration + Node index x Incremental delay duration

Value range: an integer. The unit is s. The index should be larger than 0. The modification of this parameter takes effect after reloading. For details about how to modify the parameter, see Table 2.

Default value: 3

force_promote

Parameter description: Specifies whether CM Server enables forcible switchover (that is, when the cluster status is unknown, the basic functions of the cluster are available at the cost of data loss). The value 0 indicates that forcible startup is disabled, and the value 1 indicates that forcible startup is enabled. This parameter applies to DNs.

Value range: an integer, 0 or 1. The modification of this parameter takes effect after reloading. For details about how to modify the parameter, see Table 2.

Default value: 0

switch_rto

Parameter description: Specifies the delay for the forcible switchover of CM Server. When force_promote is set to 1 and a shard in the database does not have primary CM Server, the system starts timing. After the delay, forcible switchover is executed.

Value range: an integer ranging from 60 to 2147483647. The unit is s. The modification of this parameter takes effect after reloading. For details about how to modify the parameter, see Table 2.

Default value: 600

enable_finishredo_retrieve

Parameter description: Specifies whether to retrieve data of Xlogs that have been cut off by redo after a forcible CM Server switchover. If this parameter is set to on, data is automatically retrieved after a forcible switchover.

Parameter type: Boolean

Unit: none

Value range:

• off: disabled.
• on: enabled.

Default value: off

Setting method: This is a SIGHUP parameter. Set it based on instructions provided in Table 1.

Setting suggestion: If you can accept the loss of some data caused by forcible service (system) switchover, set this parameter to on when the service recovery has the highest priority.

backup_open

Parameter description: Specifies the DR database instance settings. After this parameter is enabled, CM runs in DR database instance mode.

Value range: an integer ranging from 0 to 1. The modification takes effect after CM Server is restarted. This parameter cannot be enabled for a non-DR database instance. For details about how to modify this parameter, see Table 2.

• 0: disabled.
• 1: enabled.

Default value: 0

enable_dcf

Parameter description: Specifies the status of the DCF mode.

Value range: Boolean. The modification of this parameter takes effect after reloading. For details about how to modify the parameter, see Table 2.

• 0: disabled.
• 1: enabled.

Default value: off

install_type

Parameter description: Specifies the settings related to the DR database instance. It is used to distinguish whether the database instance is based on Dorado.

Value range: an integer ranging from 0 to 2. The modification takes effect after CM Server is restarted. This parameter cannot be enabled for a non-DR database instance. For details about how to modify this parameter, see Table 2.

• 0 indicates the database instance for which the DR relationship is not established.
• 1 indicates a Dorado-based database instance.
• 2 indicates a streaming-based database instance.

Default value: 0

enable_ssl

Parameter description: Specifies whether to enable SSL.

Value range: Boolean. After this function is enabled, the SSL certificate is used to encrypt communication. The modification takes effect after CM Server is restarted. For details about how to modify this parameter, see Table 2.

• on indicates that SSL is enabled.
• off indicates that SSL is disabled.
• Default value: off
  

  To ensure security, you are advised not to disable it. After this function is disabled, the CM does not use encrypted communication and all information is transmitted in plaintext, which may bring security risks such as eavesdropping, tampering, and spoofing.

ssl_cert_expire_alert_threshold

Parameter description: Specifies the SSL certificate expiration alarm time.

Value range: an integer. The unit is day. If the certificate expiration time is less than the value of this parameter, an alarm indicating that the certificate is about to expire is reported. The modification takes effect after CM Server is restarted. For details about how to modify this parameter, see Table 2.

Default value: 90

ssl_cert_expire_check_interval

Parameter description: Specifies the period for checking whether the SSL certificate expires.

Value range: an integer. The unit is s. The modification takes effect after CM Server is restarted. For details about how to modify this parameter, see Table 2.

Default value: 86400

delay_arbitrate_timeout

Parameter description: Specifies the waiting time for a node in the same AZ as the primary DN to be promoted to primary after redo replay.

Value range: an integer, in the range [0,21474836] (unit: second). The modification of this parameter takes effect after reloading. For details about how to modify the parameter, see Table 2.

Default value: 0

ddb_type

Parameter description: Specifies whether to switch between ETCD and DCC modes.

Value range: an integer. 0: ETCD; 1: DCC. The modification takes effect after CM Server is restarted. For details about how to modify this parameter, see Table 2.

Default value: 0

ddb_log_level

Parameter description: Sets the DDB log level.

To disable the log function, set this parameter to "NONE", which cannot be used together with the following log levels:

To enable the log function, set this parameter to one or a combination of the following log levels: "RUN_ERR|RUN_WAR|RUN_INF|DEBUG_ERR|DEBUG_WAR|DEBUG_INF|TRACE|PROFILE|OPER". If two or more log levels are used together, separate them with vertical bars (|). The log level cannot be set to an empty string.

Value range: a string containing one or a combination of the following log levels: RUN_ERR|RUN_WAR|RUN_INF|DEBUG_ERR|DEBUG_WAR|DEBUG_INF|TRACE|PROFILE|OPER. The modification of this parameter takes effect after reloading. For details about how to modify the parameter, see Table 2.

Default value: RUN_ERR|RUN_WAR|DEBUG_ERR|OPER|RUN_INF|PROFILE

ddb_log_backup_file_count

Parameter description: Specifies the maximum number of log files that can be saved.

Value range: an integer ranging from 1 to 100. The modification of this parameter takes effect after reloading. For details about how to modify the parameter, see Table 2.

Default value: 10

ddb_max_log_file_size

Parameter description: Specifies the maximum number of bytes in a log.

Value range: a string, in the range [1M,1000M]. The modification of this parameter takes effect after reloading. For details about how to modify the parameter, see Table 2.

Default value: 10M

ddb_log_suppress_enable

Parameter description: Specifies whether to enable the log suppression function.

Value range: an integer. 0: disabled; 1: enabled. The modification of this parameter takes effect after reloading. For details about how to modify the parameter, see Table 2.

Default value: 1

ddb_election_timeout

Parameter description: Specifies the DCC election timeout period.

Value range: an integer, in the range [1,600], in seconds. The modification of this parameter takes effect after reloading. For details about how to modify the parameter, see Table 2.

Default value: 3

enable_synclist_single_inst

Parameter description: Specifies whether to reduce copies to one primary and zero standby.

Parameter type: Boolean

Unit: none

Value range:

• off: This function is disabled.
• on: This function is enabled.

Default value: off

Setting method: Refer to the set cm parameters table in "Unified Database Management Tool > cm_ctl Tool Introduction" in Tool Reference. Then run the reload command for the settings to take effect.

Setting suggestion: Retain the default value.

enable_e2e_rto

Parameter description: Specifies whether to enable the E2E RTO function. After this function is enabled, the hang-up detection period and network detection timeout interval are shortened. The CM can reach the E2E RTO indicator (RTO for a single instance ≤ 10s; RTO for combined faults ≤ 30s).

Parameter type: integer

Unit: none

Value range:

• 1: enabled.
• 0: disabled.

Default value: