Note
- For V4.3.x, this parameter is available starting with V4.3.1.
- For V4.2.x, this parameter is available starting with V4.2.3.
Description
data_disk_write_limit_percentage specifies the percentage of the data disk usage that triggers write throttling. When the data disk usage reaches this threshold, the system throttles write operations to prevent the data disk from being full.
Privilege requirements
Query the parameter
The
systenant and all user tenants can query this parameter by using theSHOW PARAMETERSstatement or theGV$OB_PARAMETERSview.Modify the parameter
Only the
systenant can modify this parameter. User tenants cannot modify this parameter.
Attributes
Attribute |
Description |
|---|---|
| Type | Int |
| Default value | 0, which indicates that write throttling is disabled. |
| Value range | [0, 100) |
| Modifiable | Yes. You can use the ALTER SYSTEM SET statement to modify the parameter. |
| Effective upon OBServer node restart | No. The setting takes effect immediately. |
Considerations
This parameter specifies the threshold for write throttling. When the data disk is full, write throttling is enabled to detect the issue early. If the data disk is full, you can delete tables to release space. Otherwise, the cluster cannot be recovered.
The value of this parameter must be greater than or equal to that of data_disk_usage_limit_percentage.
We recommend that you set this parameter to (1 - memstore_limit_size/data_disk_size) * 100%, where:
- memstore_limit_size: the value of
tenant memory_size * memstore_limit_percentage. - data_disk_size: the size of the data disk configured for the tenant.
- memstore_limit_size: the value of
Examples
Set the threshold for write throttling to 90%.
obclient> ALTER SYSTEM SET data_disk_write_limit_percentage=90;