Oracle calibrate_io tips
The dbms_resource_manager package
has a nice procedure called calibrate_io which is perfect for calibrating
disk latency and throughout.
You can pass several arguments to
dbms_resource_manager.calibrate_io:
·
Maximum latency tolerance – This is the I/O per second target for the disks
(milliseconds)
·
Number of disk spindles – The number of physical disk devices
The Oracle docs provide this working example of the calibrate_io procedure.
Note the use of dbms_output.put_line to display
the disk calibration results:
SET SERVEROUTPUT
ON
DECLARE
lat
INTEGER;
iops INTEGER;
mbps INTEGER;
BEGIN
--
DBMS_RESOURCE_MANAGER.CALIBRATE_IO (<DISKS>, <MAX_LATENCY>, iops, mbps,
lat);
DBMS_RESOURCE_MANAGER.CALIBRATE_IO (2, 10, iops,
mbps, lat);
DBMS_OUTPUT.PUT_LINE ('max_iops = ' || iops);
DBMS_OUTPUT.PUT_LINE ('latency
= ' || lat);
dbms_output.put_line('max_mbps = ' || mbps);
end;
/
After running this
procedure you can view the results using the
v$io_calibration_status and for RAC, the
gv$io_calibration_status views.
You can view the output on the
dba_rsrc_io_calibrate view, showing important disk speed metrics:
-
Maximum I/O per second for the disk (or group of
disks)
-
Maximum throughout (in megabytes per second)
-
Average Disk response time (in milliseconds)
SELECT * FROM dba_rsrc_io_calibrate;
START_TIME
END_TIME
MAX_IOPS
MAX_MBPS
MAX_PMBPS
LATENCY
DISKS
--------------------
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