Technical information

13 ATTO Technology ExpressRAID for Macintosh
7 Benchmarking a Volume
ExpressRAID includes a utility for benchmarking drives to measure peak and sustained throughput for
disk reads and disk writes.
To measure disk reads and writes, use the
ExpressRAID benchmarking utility:
1 Highlight a volume in the volume window.
2 Select Benchmark from the Utilities Menu.
3 Modify test parameters.
4 Click Start.
Additional volumes can be tested by selecting
them from the menu in the lower left corner of the
benchmark utility.
Test parameters
Your benchmark results may be tuned using the
following parameters.
Max. Transfer Size
Choices: 32 KB, 128 KB, 512 KB, 2 MB, 8 MB
Default: 512 KB
The ExpressRAID Benchmark performs disk
reads and writes of varying sizes on the volume
tested. The Max. Transfer Size option determines
the size of the transfers.
To test a drive for applications which transfer
smaller blocks of data, select a smaller value, such
as 32 Kilobytes. To test a drive for applications
which transfer larger blocks of data, select a larger
transfer size.
To run benchmark tests with a 2 megabyte
maximum transfer size, allocate more memory to
ExpressRAID: quit ExpressRAID, select its icon,
select Get Info from the file menu, and change the
preferred memory setting to a higher value.
Expected Peak
Choices: 10MB/sec. to 400 MB/sec.
Default: 20 MB/sec.
Allows adjustment of the scale of the Transfer
Rate axis on the benchmark graph, adjustable
from 10 MB/sec. to 200 MB/sec. After a
benchmark test is finished, the transfer rate axis of
the graph automatically adjusts to best fit the
performance of the volume tested.
Sample Size
Choices: 1, 2, 4, 8
Default: 2
Adjusting the sample size changes the number of
times each transfer is done during the benchmark
test. The transfers are then averaged for the final
result. A larger sample size provides more
accurate results, but causes the benchmark test to
take longer.
Read and Write Tests
Choices: Enabled, Disabled
Default: Enabled
By default, ExpressRAID performs both read and
write tests on the drive being tested. These
benchmarks are non-destructive, meaning they
will not harm data on these volumes in any way.
If, however, you wish to test only disk reads or
writes, the read and write tests can be turned off
by disabling the Reads and Writes boxes.
System Disk Cache
Choices: Enabled, Disabled
Default: Disabled
The default provides a more accurate test of the
disk and SCSI bus performance. Enabling the
system disk cache provides a more accurate
assessment of overall system I/O performance.
Volume Name
Selecting the volume allows you to benchmark
several drives on the same graph so you can
compare the results. Any Macintosh-compatible
volume can be benchmarked.
Reading Benchmark results
Once the benchmark tests are completed,
ExpressRAID graphically displays the test results
and determines the peak and sustained values for
the read and write tests performed.
Read tests are shown in green and write tests in
red.
The sustained read or write, shown as a relatively
flat line on the graph, indicates the true
performance of the drive.