blktrace and blkparse are designed from the ground up to be able to operate together in a 'pipe mode' where the stdout of blktrace can be fed directly into the stdin of blkparse:
root@crownbay:~# blktrace /dev/sdc -o - | blkparse -i -
This enables long-lived tracing sessions to run without writing anything to disk, and allows the user to look for certain conditions in the trace data in 'real-time' by viewing the trace output as it scrolls by on the screen or by passing it along to yet another program in the pipeline such as grep which can be used to identify and capture conditions of interest.
There's actually another blktrace command that implements the above pipeline as a single command, so the user doesn't have to bother typing in the above command sequence:
root@crownbay:~# btrace /dev/sdc