zone_disk_balance_tolerance_percentage

Description

The zone_disk_balance_tolerance_percentage parameter controls the tolerance percentage of the disk balancing algorithm for table groups between zones. When the disk usage difference between the zone with the highest disk usage and the zone with the lowest disk usage exceeds the maximum zone disk usage multiplied by this percentage, disk balancing is triggered between zones.

Privilege requirements

• Query the parameter

  The sys tenant and all user tenants can use the SHOW PARAMETERS statement or the GV$OB_PARAMETERS view to query this parameter.

• Modify the parameter

  The sys tenant and user tenants can modify this parameter.

Attributes

Considerations

The load balancing module automatically attempts to exchange SCOPE=ZONE table groups between different zones to make the total disk usage of SCOPE=ZONE table groups as balanced as possible across zones. To control the frequency of balancing, exchanges are only attempted when the total disk usage difference of SCOPE=ZONE table groups between zones meets the following two conditions:

1. The total disk usage difference of the table groups exceeds the total disk usage of the zone with the highest disk usage multiplied by zone_disk_balance_tolerance_percentage/100.

2. The total disk usage of the zone with the highest disk usage exceeds 50 GB * number of log stream groups.

In general, the value of the zone_disk_balance_tolerance_percentage parameter should remain at the default value of 10.

• If the disk usage of SCOPE = 'ZONE' table groups changes significantly, leading to frequent disk balancing, you can increase this value to reduce the frequency of balancing.

• If you want to completely disable zone-level disk balancing, set this value to 100.

Examples

Set the tolerance percentage for zone-level disk balancing to 20%.

obclient> ALTER SYSTEM SET zone_disk_balance_tolerance_percentage = 20;