Disk IO determination best practices

The AppMon Server always reads and writes using the following block sizes:

  • Read block size: min. 1 K, max 1024 K (dynamic)
  • Write block size: 64 K

There are various types of storage types available. Keep in mind that fast onboard disks typically satisfy the I/O requirements. Often a bottleneck in terms of I/O write and read speed occurs if a SAN-based storage is used. Therefore, it is important to test the I/O performance of the available hardware. Follow the steps below to verify the I/O write and read speed.


Do not install the AppMon Server on SAN-based storage (DT_HOME). Use the internal fast onboard disk to avoid unusual performance behavior. The session storage can be on the SAN to store raw data.

How to measure available disk I/O for session storage

These tests write 32 GB of data to your disk and may take some time to complete. They generate results for write, rewrite, read, reread, random read, and random write.

Download the latest free IOzone tool for your operating system:

Execute the following commands:

For Linux For Windows
Test for WriteSpeed /opt/iozone/bin/iozone -s 32000m -r 64k -i 0 -i 1 -w -f /<installation-directory>/testwritespeed <installation-directory>/iozone -s 32000m -r64k -i 0 -i 1 -w -f testwritespeed
Test for RandomRead. Try different sizes for RandomRead, like 1 K or 1024 K to see how the disk behaves. /opt/iozone/bin/iozone -s 32000m -r 16k -i 2 -w -f /<installation-directory>/testrandomread <installation-directory>/iozone -s 32000m -r16k -i 2 -w -f testrandomread

Verify available disk I/O.

The results from these tests should match the disk I/O requirements specified in the results of the Deployment Sizing Calculator.