Random Access Flag Not Reflected Correctly in XML Output about diskspd HOT 2 CLOSED

Random access in terms of DISKSPD's IO offset pattern is on the <Random> element, not <RandomAccess>.

The <RandomAccess> element refers to / controls whether the target file is opened with FILE_FLAG_RANDOM_ACCESS or not (see CreateFile). On the command line this comes from the -f[rst] option; the adjacent sequential/temporary flags are also spec'd here.

These flags only affected OS cached operation. RANDOM_ACCESS controls whether the kernel cache manager will attempt to do readahead into the cache based on an observed sequential/strided access pattern. Saying RANDOM_ACCESS turns that off. SEQUENTIAL is the opposite - it says it will be sequential, so it more aggressively does do readahead. Again, specific to cached operation.

If you use -Rpxml (print the XML profile; no run) it should be pretty easy/quick to verify the effect on the XML.

from diskspd.

Thanks for the clarification.

from diskspd.