Introduced in Oracle Database 11g Release 1, the CALIBRATE_IO procedure gives an idea of the capabilities of the storage system from within Oracle. There are a few restrictions associated with the procedure.
- The procedure must be called by a user with the SYSDBA priviledge.
TIMED_STATISTICSmust be set to TRUE, which is the default whenSTATISTICS_LEVELis set to TYPICAL.- Datafiles must be accessed using asynchronous I/O. This is the default when ASM is used.
SQL> SQL> SELECT d.name,
2 i.asynch_io
3 FROM v$datafile d,
4 v$iostat_file i
5 WHERE d.file# = i.file_no
6 AND i.filetype_name = 'Data File';
NAME
ASYNCH_IO
+DATA/JYC/DATAFILE/system.259.1216240375
ASYNC_ON
+DATA/JYC/DATAFILE/sysaux.260.1216240429
ASYNC_ON
+DATA/JYC/DATAFILE/undotbs1.261.1216240455
ASYNC_ON
NAME
ASYNCH_IO
+DATA/JYC/86B637B62FE07A65E053F706E80A27CA/DATAFILE/system.267.1216240805
ASYNC_ON
+DATA/JYC/86B637B62FE07A65E053F706E80A27CA/DATAFILE/sysaux.268.1216240805
ASYNC_ON
+DATA/JYC/DATAFILE/users.262.1216240455
ASYNC_ON
NAME
ASYNCH_IO
+DATA/JYC/86B637B62FE07A65E053F706E80A27CA/DATAFILE/undotbs1.269.1216240805
ASYNC_ON
+DATA/JYC/DATAFILE/undotbs2.271.1216241127
ASYNC_ON
+DATA/JYC/42B133224FC259CDE0634CCFA8C0B908/DATAFILE/system.276.1216241607
ASYNC_ON
NAME
ASYNCH_IO
+DATA/JYC/42B133224FC259CDE0634CCFA8C0B908/DATAFILE/sysaux.277.1216241607
ASYNC_ON
+DATA/JYC/42B133224FC259CDE0634CCFA8C0B908/DATAFILE/undotbs1.275.1216241607
ASYNC_ON
+DATA/JYC/42B133224FC259CDE0634CCFA8C0B908/DATAFILE/undo_2.279.1216241665
ASYNC_ON
NAME
ASYNCH_IO
+DATA/JYC/42B133224FC259CDE0634CCFA8C0B908/DATAFILE/users.280.1216241667
ASYNC_ON
13 rows selected.Elapsed: 00:00:00.17
SQL> show parameter STATISTICS_LEVEL ;
NAME TYPE VALUE
client_statistics_level string TYPICAL
statistics_level string TYPICAL
SQL>
oracle@rac1:/home/oracle\]$ sqlplus / as sysdba SQL\*Plus: Release 19.0.0.0.0 - Production on Sun Nov 23 14:07:13 2025 Version 19.9.0.0.0 Copyright (c) 1982, 2020, Oracle. All rights reserved. Connected to: Oracle Database 19c Enterprise Edition Release 19.0.0.0.0 - Production Version 19.9.0.0.0 SQL\> show pdbs; CON_ID CON_NAME OPEN MODE RESTRICTED ---------- ------------------------------ ---------- ---------- 2 PDB$SEED READ ONLY NO 3 PDB READ WRITE NO SQL\> alter session set container=pdb; Session altered. SQL\> SET SERVEROUTPUT ON DECLARE l_latency PLS_INTEGER; l_iops PLS_INTEGER; l_mbps PLS_INTEGER; BEGIN DBMS_RESOURCE_MANAGER.calibrate_io (num_physical_disks => 1, max_latency => 20, max_iops => l_iops, max_mbps => l_mbps, actual_latency => l_latency); DBMS_OUTPUT.put_line('Max IOPS = ' || l_iops); DBMS_OUTPUT.put_line('Max MBPS = ' || l_mbps); DBMS_OUTPUT.put_line('Latency = ' || l_latency); END; / SQL\> DECLARE \* ERROR at line 1: ORA-65040: operation not allowed from within a pluggable database ORA-06512: at "SYS.DBMS_RMIN_SYS", line 4469 ORA-06512: at "SYS.DBMS_RESOURCE_MANAGER", line 1210 ORA-06512: at line 6 SQL\> conn / as sysdba Connected. SQL\> show pdbs; CON_ID CON_NAME OPEN MODE RESTRICTED ---------- ------------------------------ ---------- ---------- 2 PDB$SEED READ ONLY NO 3 PDB READ WRITE NO SQL\> set timing on SQL\> SET SERVEROUTPUT ON DECLARE l_latency PLS_INTEGER; l_iops PLS_INTEGER; l_mbps PLS_INTEGER; BEGIN DBMS_RESOURCE_MANAGER.calibrate_io (num_physical_disks =\> 1, max_latency =\> 20, max_iops =\> l_iops, SQL\> 2 3 4 5 6 7 8 9 max_mbps =\> l_mbps, 10 actual_latency =\> l_latency); 11 12 DBMS_OUTPUT.put_line('Max IOPS = ' \|\| l_iops); 13 DBMS_OUTPUT.put_line('Max MBPS = ' \|\| l_mbps); 14 DBMS_OUTPUT.put_line('Latency = ' \|\| l_latency); 15 END; 16 / max_iops = 157 latency = 49.277 max_mbps = 19 Note: The high I/O latencies from the calibration run indicate that the calibration I/Os are being serviced mostly from disk. If your storage has a cache, you may achieve better results by rerunning. Rerunning will warm or populate the storage cache. Max IOPS = 157 Max MBPS = 19 Latency = 49 PL/SQL procedure successfully completed. Elapsed: 00:09:13.27 SET LINESIZE 100 COLUMN start_time FORMAT A20 COLUMN end_time FORMAT A20 SELECT TO_CHAR(start_time, 'DD-MON-YYY HH24:MI:SS') AS start_time, TO_CHAR(end_time, 'DD-MON-YYY HH24:MI:SS') AS end_time, max_iops, max_mbps, max_pmbps, latency, num_physical_disks AS disks FROM dba_rsrc_io_calibrate; SQL\> SET LINESIZE 100 SQL\> COLUMN start_time FORMAT A20 SQL\> COLUMN end_time FORMAT A20 SQL\> SQL\> SELECT TO_CHAR(start_time, 'DD-MON-YYY HH24:MI:SS') AS start_time, 2 TO_CHAR(end_time, 'DD-MON-YYY HH24:MI:SS') AS end_time, 3 max_iops, 4 max_mbps, 5 max_pmbps, 6 latency, 7 num_physical_disks AS disks 8 FROM dba_rsrc_io_calibrate; START_TIME END_TIME MAX_IOPS MAX_MBPS MAX_PMBPS LATENCY DISKS -------------------- -------------------- ---------- ---------- ---------- ---------- ---------- 23-NOV-025 14:07:45 23-NOV-025 14:16:58 157 19 19 49.277 1 Elapsed: 00:00:00.07 SQL\>  [https://oracle-base.com/articles/misc/measuring-storage-performance-for-oracle-systems](https://oracle-base.com/articles/misc/measuring-storage-performance-for-oracle-systems "https://oracle-base.com/articles/misc/measuring-storage-performance-for-oracle-systems")