I have verified that building a clean v4.12 with 68c59fcea1f2c6a54c62aa896cc623c1b5bc9b47 cherry picked on top still shows the problem: [root@backup2 ~]# mtx -f /dev/sg7 next 0 Unloading drive 0 into Storage Element 45...mtx: Request Sense: Long Report=yes mtx: Request Sense: Valid Residual=no mtx: Request Sense: Error Code=0 (Unknown?!) mtx: Request Sense: Sense Key=No Sense mtx: Request Sense: FileMark=no mtx: Request Sense: EOM=no mtx: Request Sense: ILI=no mtx: Request Sense: Additional Sense Code = 00 mtx: Request Sense: Additional Sense Qualifier = 00 mtx: Request Sense: BPV=no mtx: Request Sense: Error in CDB=no mtx: Request Sense: SKSV=no MOVE MEDIUM from Element Address 1 to 1045 Failed Nothing appears to be logged; is there any kind of debugging information I can collect which might help to track this down? I'm not particularly good at this but I am pretty sure that I'm building everything properly and am actually booting the patched kernel. - J<