Both SQLIOSim and SQLIOStress use DeviceIOControl to determine information about the target.
On disk caches are typically not battery backed and when enabled can lead to data loss during a power outage. The utilities attempt to warn the user when on disk caching is reported as enabled.
Not all devices support interrogation of the disk cache setting. SQLIOSim logs an error condition when unable to determine the on disk cache setting instead of a warning.
Error Text: The request could not be performed because of an I/O device error.
Description: Unable to get disk cache info for E:\
The next release of SQLIOSim won't consider this an error condition, instead a warning.
Note: As the system administrator you should validate the on disk cache settings of your system.
SQL Server Senior Escalation Engineer