After watching the trouble recur, I see that the device associated with the changer SCSI device ID moved: it was /dev/sg2, today it is /dev/sg1. No changes were made to the Exabyte LTO-2 tape library  or to the SCSI card (or anything else). So there is something I'm failing to understand about udev, SCSI or the Exabyte.

 

Perhaps during bootup I should attempt

 

mtx -f /dev/sg0 status

mtx -f /dev/sg1 status

 

until I have a valid status, and link

/dev/changer to that, then refer to /dev/changer in amanda.conf. That's a workaround: somehow the device assigned to the changer moves on occasion, after a reboot. Perhaps I should be referring to the changer device in some other way (bus number, SCSI ID, lun...).

 

Thanks again.

 

FL