@ Charles Polisher yes, seems that avgrq-sz does provide the info I needed, thanks for pointing that out! @ Keith I am not sure if blktrace can monitor which files being written to disk or if it is the best tool for that. But you could check out the inotify-tools (iwatch and related) which go on that directions. An example usage is here http://openquery.com/blog/tool-day-inotify or iwatch http://iwatch.sourceforge.net/index.html cheers Antonello