How to Use Oracle Orion for Accurate IO Performance Testing

Orion Overview

Orion is an I/O performance testing tool provided by Oracle. It can run without installing the Oracle Database software or creating a database, and can simulate Oracle database I/O load as well as ASM striping. It measures IOPS, MB/s, and latency for random or sequential I/O of specified block sizes.

Since Oracle Database 11g, Orion is bundled with Grid Infrastructure and the database software, so the executable can be found in $GRID_HOME/bin or $ORACLE_HOME/bin.

Advantages and Disadvantages

Advantages

Flexible I/O workload specification (e.g., small random I/O, large sequential I/O).

No need for a load runner or recording actions.

No requirement to run an Oracle database or prepare large test data sets.

Results reflect realistic storage behavior; random I/O tests can drive cache hit rate to near zero, exposing true disk IOPS and MB/s, which many stress tools cannot achieve.

Read/write ratios can be customized.

Disadvantages

Test duration and load are not user‑configurable; the whole test runs automatically.

Cannot simulate certain operations such as full table scans, full index scans, or bulk data loads.

Getting Started with Orion

Choose a name for the -testname parameter; this identifier is used for the run and for naming result files. If omitted, “orion” is used.

Create an input file named for the test (e.g., mystest.lun) and list the devices to be tested, one per line, such as:

/dev/raw/raw1
/dev/raw/raw2
# or
/dev/sdb1
/dev/sdc1

Verify that the devices are accessible, e.g.: dd if=/dev/raw/raw1 of=/dev/null bs=32k count=1024 Ensure the system has the libaio library installed (required for asynchronous I/O). Linux kernels 2.6+ include the libaio RPM by default.

Run a simulated OLTP workload, for example:

./orion_linux_x86 -run oltp -testname mytest

Sample Test Scenarios

1. 8 KB Random Read

./orion_linux_x86-64 -run advanced -num_large 0 -size_small 8 -type rand -simulate raid0 -write 0 -duration 120 -matrix row -testname mytest

The tool reports an estimated run time of about 23 minutes; the duration cannot be changed.

Result files generated include: mytest_..._trace.txt – detailed trace information. mytest_..._summary.txt – overall summary. mytest_..._mbps.csv – MB/s results for large I/O (not created in this run). mytest_..._lat.csv – latency for small I/O. mytest_..._iops.csv – IOPS for small I/O.

Sample output shows maximum small IOPS of 28 394 at 120 KB size and minimum latency of 0.17 ms.

2. 8 KB Random Write

./orion_linux_x86-64 -run advanced -num_large 0 -size_small 8 -type rand -simulate raid0 -write 100 -duration 120 -matrix row

3. 1 MB Sequential Read

./orion_linux_x86-64 -run advanced -num_small 0 -size_large 1024 -type seq -simulate raid0 -write 0 -duration 120 -matrix col

Issue Encountered and Fix

During the first test run an asynchronous I/O error occurred on one host, while another host with an installed Oracle database completed successfully. The root cause was an incorrect sysctl.conf setting. Adding the appropriate kernel parameters resolved the error.