2012-10-22 bus issue after running Blackmagic Disk Speed Test.app during a backup
Whilst screenshots there do not show Blackmagic Disk Speed Test (sorry), my recollection is that problems began after I selected – in that app – what I believed to be the ZFS file system gjp22 that is my home directory. That belief, based on the home icon in the sheet presented by the app …
… I also vaguely recall there being more than two listings for gjp22 (it's often normal to have two, one of which is a read-only backup; abnormal to see three or more).
In retrospect, I wonder whether iconography was confused and if so: whether something other than writeable volume gjp22 was truly selected.