By feeding the SYSLOG (or a selection of the SYSLOG as long as it has the ARC-messages) into the following SAS you get a nice report showing the times and durations of your HSM tasks.

The SAS assumes the SYSLOG file is a file spanning the period of no more than one 24 hour period.
How is this graph created?
Just downlaod the source : http://www.savefile.com/files/1528255
And there you have the complete source to craft your very own HSM activity Graphs!