Databases Reference
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This test is a perfect demonstration of how a system can fail to utilize its maximum potential perfor-
mance. Only eight outstanding I/Os completed, which failed to push the I/O subsystem. To properly
test a given system, it is a good idea to scale the workload dynamically to determine how it will per-
form under increasing loads. To accomplish this you can script SQLIO:
sqlio -kR -s300 -frandom -o1 -b8 -LS -Fparam.txt
sqlio -kR -s300 -frandom -o2 -b8 -LS -Fparam.txt
sqlio -kR -s300 -frandom -o4 -b8 -LS -Fparam.txt
sqlio -kR -s300 -frandom -o8 -b8 -LS -Fparam.txt
sqlio -kR -s300 -frandom -o1 -b16 -LS -Fparam.txt
sqlio -kR -s300 -frandom -o1 -b32 -LS -Fparam.txt
sqlio -kR -s300 -frandom -o1 -b64 -LS -Fparam.txt
sqlio -kR -s300 -frandom -o1 -b128 -LS -Fparam.txt
sqlio -kR -s300 -frandom -o1 -b256 -LS -Fparam.txt
Run this batch i le from the command line and capture the results to an output i le:
RunSQLIO.bat > Result.txt
Ideally, you will test several different scenarios. Create a batch i le with each scenario that scales
from 1 to 256 outstanding I/Os, such as the following:
➤
Small-block random read performance:
sqlio -kR -s300 -frandom -o1 -b8 -LS -Fparam.txt
➤
Small-block random write performance:
sqlio -kW -s300 -frandom -o1 -b8 -LS -Fparam.txt
➤
Large-block sequential read performance:
sqlio -kR -s300 - fsequential -o1 -b8 -LS -Fparam.txt
➤
Large-block sequential write performance:
sqlio -kR -s300 -fsequential -o1 -b8 -LS -Fparam.txt
Running these scenarios as a single batch i le will automate the I/O system testing process. The most
important data points are the latency and performance measurements. When the tests exceed your
maximum latency tolerance, usually not more than 20 milliseconds, you have exceeded the capabili-
ties of your I/O subsystem. If the system does not meet your overall performance requirements with
adequate response times, then you need to investigate the system for errors or coni guration issues.
Ultimately, you may need to optimize the storage system's performance to ensure that previously
specii ed requirements are met.
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