The combination of the observed file contents after several seconds of writing with the behavior difference in all 0s vs all 1s I/O in our fio experiments made me pretty confident about the conclusion we reached, but we should be sure.
To be 100% certain, I just hooked CreateFileA to remove the FILE_FLAG_DELETE_ON_CLOSE. Examining ATTO’s I/O file after it completes shows that it does indeed contain only 0s.
Tomorrow I can also try with ATTO hooked to write all 1s instead of all 0s to observe the performance difference directly in ATTO. (I’m away from the drives that exhibit the performance difference at the moment.)
Your point is a good one. Thanks for raising it.
The combination of the observed file contents after several seconds of writing with the behavior difference in all 0s vs all 1s I/O in our fio experiments made me pretty confident about the conclusion we reached, but we should be sure.
To be 100% certain, I just hooked
CreateFileAto remove theFILE_FLAG_DELETE_ON_CLOSE. Examining ATTO’s I/O file after it completes shows that it does indeed contain only 0s.Tomorrow I can also try with ATTO hooked to write all 1s instead of all 0s to observe the performance difference directly in ATTO. (I’m away from the drives that exhibit the performance difference at the moment.)