data_disk_write_limit_percentage

Description

data_disk_write_limit_percentage specifies the maximum usage of the data disk allowed for data writes, in percentage. When the usage of the data disk is close to the specified value, the system limits write operations from business requests to prevent the data disk from running out of space.

Limitations

• Query the parameter

  In the sys tenant or a user tenant, you can execute the SHOW PARAMETERS statement to query the parameter or query the GV$OB_PARAMETERS view for the parameter. In the sys tenant, you can also query the information_schema.PARAMETERS view for the parameter.

• Modify the parameter

  You can modify the parameter only in the sys tenant.

Attributes

Considerations

• This parameter controls the system to stop writing data to the data disk when the data disk usage reaches the specified upper limit. This way, you can identify problems as soon as possible and delete tables to urgently release space, thus facilitating cluster restore.

• The value of this parameter must be greater than or equal to the value of the data_disk_usage_limit_percentage parameter.

• We recommend that you set this parameter by using the following formula: (1 -memstore_limit_size/data_disk_size) × 100%. The parameters in the formula are described as follows:

  • memstore_limit_size: the maximum size of MemStores, which is equal to memory_size × memstore_limit_percentage.
  • data_disk_size: the size of the data disk.

Example

Set the maximum usage of the data disk allowed for data writes to 90%.

obclient> ALTER SYSTEM SET data_disk_write_limit_percentage=90;

References

memstore_limit_percentage