Quote Originally Posted by Ao1 View Post
OK now I’m confused. I thought hIOmon could only monitor TRIM commands issued from the OS. Are you saying that hIOmon can tell if the SSD actually executed them?
The hIOmon software does observe TRIM I/O operations as they occur within the I/O stack of the OS.

TRIM I/O operations that are observed at the "physical device level" within the I/O stack are generally passed further down the stack, e.g., through the HBA out to the actual device (in which case the proper, corresponding TRIM device command, in accordance with the interface protocol, e.g., ATA, is issued to the device).

Now when the respective TRIM command has completed at the device (i.e., the device has acknowledged the receipt of the TRIM command and its associated parameters such as the DSRs - and possibly also performed some additional actions, see below), the device returns "completion status" for the TRIM command. This completion status, in turn, "flows" back up through the HBA and upward through the I/O stack in the OS. So consequently, the hIOmon software subsequently observes the "completion status" associated with the respective TRIM I/O operation (i.e., essentially whether the TRIM command was at least successfully received and acknowledged).

As suggested within your prior post #4 (and as noted within the following post), what exactly the device/SSD actually does with the "trimmed" blocks/sectors that were indicated by the TRIM commands it has received (and when) is, I believe, basically "vendor-specific" at the current time.

http://www.xtremesystems.org/forums/...&postcount=156

So overall, the hIOmon software can basically observe whether the respective TRIM commands were successfully issued (i.e., whether the TRIM device commands were successfully received and acknowledged) and the corresponding time duration that it took to "perform" the individual TRIM I/O operations, but what particular actions and when these actions are undertaken by the SSD as a result of these TRIM commands can be another matter (which is currently device/vendor specific).