Most people do not seem to adequately recognize the important role the location of java.io.tmpdir plays in DAM asset ingestions.

Below is an illustration from a test performed on Windows 7 (uploaded 400 (1 MB) JPG images to AEM 6.1 TarMK crx3tar /Java 8) - the monitoring tool used was Mark Russinovich’s Process Monitor.

61% of total disk I/O (in bytes) happens at the location of java.io.tmpdir. For performance reasons, direct it towards your most performant disk (locally-attached, such as the ephemeral disk volumes on the Amazon Cloud).

Another interesting observation - 400 MB of JPGs will cause about 2.5 GB worth of disk WRITES and 3.3 GB worth of disk READs.

NOTE: You control the location of java.io.tmpdir by passing the following init argument to the JVM (in start.bat):