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Today we are going to discuss the NT Storage Device Stack in brief. I am sure most of you would have encountered a server hang issue where the one of the Antivirus or Storage driver was pointed out to be the root cause of the issue. It is important to understand the layers which are in picture when you are trying to write a file to the disk, because every I/O operation in windows is done via IRPs (I/O Request Packets - Data structures representing the I/O) and these IRPs have to pass through all the layers to achieve the completion of the task and any of these layer can potentially block the I/O from completion mostly due to code bug or at times due to the workload. NT-based operating system class and filter drivers for peripheral storage devices act as an interface between any intermediate or highest level drivers layered above the class or filter driver and a system-supplied port driver. I/O requests from a user application or kernel component reach storage class drivers through ...