Quote Originally Posted by Ao1 View Post
Hi overthere. Yes I'm using MS Essentials.
Hi Ao1,

As I suspected. Basically the read I/O operations (with a data transfer size of 32,768 bytes) that you see within your "read" table of metrics are due to MSE.

That, of course, leaves the big question of: "Where did all of the AS SSD read I/O operations go?"

The answer is: AS SSD performed the read I/O operations to the physical device directly at the physical device level within the OS I/O stack.

That is, none of these read I/O operations were issued by AS SSD as file I/O operations directed to a "test.bin" file - and so these read I/O operations were not observed by hIOmon at either the file level or at the physical volume level within the OS I/O stack (since the hIOmon software was ostensibly configured to only monitor file I/O operations along with I/O operations at the physical volume level, as shown within your tables of metrics).

Now if the hIOmon software had been configured to (also) monitor the physical device level I/O operations, then the hIOmon I/O Monitor would have observed 26,214 read I/O operations (all but one of which were random) with a data transfer size of 4,096 bytes issued to "\Device\Harddisk0\DR0:\<DASD>" (assuming you ran AS SSD against physical drive 0) for a total combined read data transferred amount of 107,372,544 bytes. (There was actually another read I/O operation with a data transfer length of zero - but that's another story ).

BTW, I cheated and configured the hIOmon software to monitor at all three levels within the OS I/O stack concurrently.

In short, you have brought forth a good example that shows the importance (I believe) of being able to optionally monitor I/O operations at the three different levels within the I/O stack (and, better yet, concurrently if and when needed).

This highlights another nuance of which I suspect many folks at not aware. Just as it is possible for I/O operations to only be performed at the "file-level" (e.g., those that are satisfied by the system file cache), it is also possible for applications to perform I/O operations that essentially bypass the file system (as AS SSD has done with read I/O operations in this case).