Using CALIBRATE_IO
Using Oracle’s Resource Manager requires you to understand the IO dynamics. The first step requires you to run the CALIBRATE_IO procedure from the DBMS_RESOURCE_MANAGER package.
Oracle provides some great examples about how to use the CALIBRATE_IO procedure of the DBMS_RESOURCE_MANAGER package in the Oracle Database Database PL/SQL Packages and Types Reference. The CALIBRATE_IO procedure returns the best answer when you provide a valid number of files, which you can capture by querying the V$ASM_DISK view.
The following code queries the view and assigns the value to a session level variable:
CLEAR BREAKS CLEAR COLUMNS CLEAR COMPUTES VARIABLE files NUMBER BEGIN SELECT COUNT(DISTINCT name) disks INTO :files FROM v$asm_disk; END; / |
When you have the number of files, you can calibrate the IO with the following anonymous block. The query should always work but just in case the NVL function on line 9 assigns the default number of files.
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 | DECLARE lv_num_physical_disks BINARY_INTEGER; — v$asm_disk lv_max_latency BINARY_INTEGER := 10; lv_max_iops BINARY_INTEGER; lv_max_mbps BINARY_INTEGER; lv_actual_latency BINARY_INTEGER; BEGIN /* Assign actual files to anonymous block variable. */ lv_num_physical_disks := NVL(:files,2); /* Run the calibrate_io procedure. */ DBMS_RESOURCE_MANAGER.CALIBRATE_IO( num_physical_disks => lv_num_physical_disks , max_latency => lv_max_latency , max_iops => lv_max_iops , max_mbps => lv_max_mbps , actual_latency => lv_actual_latency); END; / |
You can query the results like this:
SELECT max_iops , max_mbps , max_pmbps , latency , num_physical_disks FROM dba_rsrc_io_calibrate; |
It should show results like these:
MAX_IOPS MAX_MBPS MAX_PMBPS LATENCY NUM_PHYSICAL_DISKS
-------- -------- --------- ------- ------------------
8894 443 294 9 18 |
Hope this helps those using the CALIBRATE_IO procedure of the DBMS_RESOURCE_MANAGER package.
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