Modify configurations of a resource unit

You can modify the CPU, memory, and log disk configurations of a resource unit.

Considerations

If you want to upgrade the configurations of a resource unit that is being used by a tenant, make sure that the OBServer node has sufficient resources for allocation. You can query the oceanbase.GV$OB_SERVERS view for the total resources and allocated resources of the node and determine whether the configurations of the resource unit can be modified based on calculation.

To upgrade the configurations of a resource unit, make sure that the total amounts of resources after the modification meet the following requirements:

Sum(min_cpu) <= CPU_CAPACITY;
Sum(max_cpu) <= CPU_CAPACITY * resource_hard_limit;
Sum(memory_size) <= MEM_CAPACITY;
Sum(log_disk_size) <= LOG_DISK_CAPACITY;

Parameters:

• CPU_CAPACITY: the total CPU capacity.

• MEM_CAPACITY: the total memory capacity.

• LOG_DISK_CAPACITY: the total capacity of the log disk.

  The total capacity of the log disk is jointly controlled by the log_disk_size and log_disk_percentage parameters. log_disk_size specifies the size of the disk where REDO logs are stored, and the default value is 0. log_disk_percentage specifies the percentage of the disk space occupied by REDO logs, and the default value is 0. The rules for using the two parameters are described in the following list:

  • If the value of log_disk_size is 0 but the value of log_disk_percentage is not 0, the system allocates log disk space based on the value of log_disk_percentage.

  • If the value of log_disk_size is not 0, the system allocates log disk space based on the value of log_disk_size, regardless of whether the value of log_disk_percentage is 0.

  • If the values of both log_disk_size and log_disk_percentage are 0, the system automatically calculates the percentage of the disk space occupied by REDO logs. The percentage depends on whether the disk is shared by REDO logs and data.

    • If the disk is shared, the percentage of the disk space occupied by REDO logs is 30%.

    • If the disk is exclusive for REDO logs, the percentage of the disk space occupied by REDO logs is 90%.

  For more information about the log_disk_size parameter, see log_disk_size.

  For more information about the log_disk_percentage parameter, see log_disk_percentage.

• resource_hard_limit: a specific system parameter.

  The system allocates CPU resources based on the value of the resource_hard_limit parameter. Value range: [1,10000]. The default value is 100, indicating that over-allocation is not allowed.

  For more information about the resource_hard_limit parameter, see resource_hard_limit.

To downgrade the configurations of a resource unit, make sure that the total amounts of resources including the CPU, memory, and log disk capacity are greater than or equal to the used resources of the disk.

Limitations

Only the sys tenant can modify resource unit configurations.

Procedure

You can modify one or more of the CPU, memory, IOPS, and log disk configurations of a resource unit. The configurations that are not modified remain unchanged.

1. Log on to the sys tenant of the cluster as the root user.

2. Modify the configurations of a resource unit.

   Sample statement:

   ALTER RESOURCE UNIT unitname
   MAX_CPU [=] cpunum,
   [MIN_CPU [=] cpunum,]
   MEMORY_SIZE [=] memsize,
   [MAX_IOPS [=] iopsnum, MIN_IOPS [=] iopsnum,IOPS_WEIGHT [=]iopsweight,]
   [LOG_DISK_SIZE [=] logdisksize];
   

   Modify the configurations of the unit1 resource unit.

   obclient> ALTER RESOURCE UNIT unit1 MAX_CPU 15, MEMORY_SIZE '20G', LOG_DISK_SIZE '4G';