update with resolution and some possibly useful information. resolution: Format & recreate usb start up disk. On boot my usb drive was assigned sdb (in fact looking at my dmesg above it was anyway..) upon reboot my df output looked 'normal' (/cdrom was mounted from /dev/sdb1) and the install progressed without issue.
useful information: This usb disk was initially booted on the same system *without* the hard disk attached, in which case I would have expected the usb disk (/cdrom mount point) to be assigned sda. It seems that with the usb disk this information persists across reboots, at least partially anyway and in some cases can prevent installs from completing (this is my educated guess - I haven't tried to reproduce it a second time). -- usb startup disk failed to unmount /cdrom when change partition tables https://bugs.launchpad.net/bugs/292493 You received this bug notification because you are a member of Ubuntu Bugs, which is subscribed to Ubuntu. -- ubuntu-bugs mailing list [email protected] https://lists.ubuntu.com/mailman/listinfo/ubuntu-bugs
