Backup and Restoration

operation_mode

Parameter description: Specifies whether the system enters the backup and restoration mode.

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

Value range: Boolean

• on indicates that the system is in the backup and restoration mode.
• off indicates that the system is not in the backup and restoration mode.

Default value: off

enable_cbm_tracking

Parameter description: Specifies whether to enable cbm tracking. To perform full or incremental backup for the cluster by using Roach, set this parameter to on. Otherwise, the backup will fail.

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

Value range: Boolean

• on: The cbm tracking is enabled.
• off: The cbm tracking is disabled.

Default value: off

max_size_for_xlog_retention

Parameter description: Specifies when to forcibly update the backup replication slot or logical replication slot to prevent the disk from being full and the cluster from being read-only because logs cannot be recycled during backup or logical decoding. It is recommended that the value of this parameter be a little smaller than the value of datastorage_threshold_value_check of the CM Server component to prevent the cluster from entering the read-only state.

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

Value range: –100 to 2147483647

• The value 0 indicates that this function is disabled.
• A negative value indicates that the backup replication slot or logic replication slot is forcibly updated when the disk usage exceeds the threshold and logs are recycled due to blocked backup operation or logic decoding. For example, –80 indicates that the disk usage exceeds 80% of the threshold.
• A positive value indicates that the backup replication slot or logic replication slot is forcibly updated when the size of stacked logs exceeds the threshold and logs are recycled due to blocked backup operation or logic decoding. For example, 32 indicates that the backup replication slot lags behind the redo location of the current checkpoint by more than 32 log segments. (The size of each log segment is 16 MB.)

Default value: –80

max_cbm_retention_time

Parameter description: Specifies the interval at which CBM backup files are forcibly recycled. If CBM files cannot be recycled during backup, the disk will be full and the cluster will be read-only. You are advised to set this parameter based on the full backup interval.

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

Value range: 86400 to 2147483647

• The unit is second.
• The minimum value is 1 day.
• The default value is 2 weeks.

Default value: 1209600

enable_standby_move_buckets

Parameter description: Specifies whether a CN is allowed to connect to a standby node to move buckets. This parameter is used only for cluster-level restoration.

When restoring the backup set generated during hash bucket redistribution, this parameter is used to establish a connection with the standby DN when the CN sends the buckets migration command to the DN. This parameter takes effect only in this connection. In other cases, the value is off.

Parameter type: Boolean.

Unit: none

Default value: off

Setting method: This is a BACKEND parameter and cannot be set or reloaded using gs_guc. This parameter does not take effect when written into the configuration file. It is used only as an O&M parameter for data restoration.

Setting suggestion: You are advised to retain the default value.