The soon to be released smartmontools 5.34 uses the READ DEFECT DATA command on SCSI disks. A disk that has defect list entries (or worse, an increasing number of them) is at risk. Currently the first invocation of smartctl causes this: scsi: unknown opcode 0x37 message to appear the console and in the log. The READ DEFECT DATA SCSI command does not change the state of a disk. Its opcode (0x37) is valid for SBC devices (e.g. disks) and SMC-2 devices (media changers) where it is called INITIALIZE STATUS ELEMENT WITH RANGE and again doesn't change the external state of the device. The patch is against lk 2.6.13 . Changelog: - mark SCSI opcode 0x37 (READ DEFECT DATA) as safe_for_read Signed-off-by: Douglas Gilbert Doug Gilbert