Place a checkmark on this option to configure busTRACE to automatically perform a data corruption analysis each time you stop the capture process.

An underrun occurs when a device transfers less data than what is available in the data buffer. An overrun occurs if a device wants to transfer more data than is available in the data buffer. Unfortunately, the SCSI_REQUEST_BLOCK structure is defined to return a SRB_STATUS_DATA_OVERRUN value in the SrbStatus field whether it's a data underrun OR a data overrun. The subsequent Irp status would be STATUS_BUFFER_OVERFLOW.

Data underruns are usually not error conditions while data overruns are always error conditions. This presents a problem for busTRACE since one status code represents both conditions. By default, busTRACE will try and detect if it's an underrun or overrun. If the checkmark is left disabled on this option (the default), we will filter out any underrun conditions and not report them as an error. If this checkmark is set, whenever the SrbStatus value is set to SRB_STATUS_DATA_OVERRUN, we will always report it as an error.

Let's give an example as to why underrun conditions are normally not a fatal error. Let's assume that you send a 240 byte buffer sent with an Inquiry CDB. Let's assume the device only has 36 bytes of Inquiry data. In this example, we have an underrun condition but it is not an error. In fact, this is quite common especially when dealing with Inquiry CDBs. In order for busTRACE to not confuse you, we default to not reporting any underrun condition as an error.

NOTE: This option only applies to SCSI Request Blocks (SRBs) and Storage Request Blocks (exSRBs).

If busTRACE is configured to show you interleaved I/O activity, leaving a checkmark on this option will cause busTRACE to highlight the point where the I/O starts (i.e. going down the I/O stack) as well as where the I/O finishes (i.e. going up the I/O stack). A gradient background color is used to visually show you where the I/O starts, where it finishes, and what other I/O activity might be occurring in between.

This feature is only available when you have busTRACE configured to sort I/O activity on the Counter column in ascending order (i.e. the default setting).

For some I/O activity, such as MPIO or some USB activity, the same I/O Request Packet (IRP) is used and captured multiple times. For example, with MPIO, you may have a IRP sent to a virtual device and then that same IRP sent to a physical device. Once the physical device IRP completes, the virtual device IRP completes.

This option configures busTRACE as to how you want the interleave indicators draw. With this option disabled, if you have the same IRP being used for a virtual and physical device (as one example), you would see something like this:

In the above example, you can see how I/O counter 41 is wrapped by I/O 40. You can also see by the "IRP Pointer" value, this is the exact same IRP.

If you take this exact same example, but this time place a checkmark next to this "Show single interleave indicator for lifetime of one I/O request" setting, you will see this:

In the above example, we notice that the "Interleave" column now only shows one indicator line for the one IRP that is being processed. The red arrow for I/O #41 allows you to see the wrapped nature of the captured I/O request.

Understanding how the same IRP is sent from one device stack down to another device stack is a complex topic. The above example is its simplest form but can get far more complex, particularly with MPIO. If you are uncertain, you can simply leave this option disabled and you will see an arrow indicator for each individual I/O.

Because spreadsheet programs tend to not understand hex data values, selecting this option will ensure that we always export data values to decimal to CSV or XML files.

busTRACE detects if your system has multiple cores / processors and will utilize the multiple processors during time consuming tasks, such as when busTRACE analyzes all of your captured I/Os for defects once you stop the capture process. You can remove the checkmark from this option if you want to disable this option. Note that if your computer only has a single core (i.e. only one CPU), then this option will be disabled.

Some drives, particularly port drivers, send CDB requests destined for an actual device through the host adapter device object. By enabling this option, you configure busTRACE to show you the I/O as being processed by the actual SCSI device and not the SCSI host adapter. This option is enabled by default.