user@user-laptop:~$ dmesg|tail -n 40
[ 1212.336042] usb 4-2: new low speed USB device using ohci_hcd and address 18
[ 1212.752027] usb 4-2: device not accepting address 18, error -62
[ 1212.928029] usb 4-2: new low speed USB device using ohci_hcd and address 19
[ 1213.344026] usb 4-2: device not accepting address 19, error -62
[ 1213.344055] hub 4-0:1.0: unable to enumerate USB device on port 2
[ 1330.440036] usb 4-2: new low speed USB device using ohci_hcd and address 20
[ 1330.662347] usb 4-2: configuration #1 chosen from 1 choice
[ 1330.673808] input: A4Tech USB Optical Mouse as /devices/pci0000:00/0000:00:04.0/usb4/4-2/4-2:1.0/input/input14
[ 1330.673968] a4tech 0003:09DA:0006.0004: input,hidraw0: USB HID v1.00 Mouse [A4Tech USB Optical Mouse] on usb-0000:00:04.0-2/input0
[ 1539.657236] hub 2-0:1.0: unable to enumerate USB device on port 1
[ 1545.029039] usb 4-1: new full speed USB device using ohci_hcd and address 21
[ 1545.244218] usb 4-1: configuration #1 chosen from 1 choice
[ 1545.254301] scsi8 : SCSI emulation for USB Mass Storage devices
[ 1545.256166] usb-storage: device found at 21
[ 1545.256170] usb-storage: waiting for device to settle before scanning
[ 1550.261568] usb-storage: device scan complete
[ 1550.268431] scsi 8:0:0:0: CD-ROM SAMSUNG SGH-Z810 Install 2.31 PQ: 0 ANSI: 2 CCS
[ 1550.301250] sr1: scsi3-mmc drive: 0x/0x caddy
[ 1550.301431] sr 8:0:0:0: Attached scsi CD-ROM sr1
[ 1550.301522] sr 8:0:0:0: Attached scsi generic sg2 type 5
[ 1550.487136] sr1: CDROM (ioctl) error, command: Xpwrite, Read disk info 51 00 00 00 00 00 00 00 02 00
[ 1550.487153] sr: Sense Key : Hardware Error [current]
[ 1550.487157] sr: Add. Sense: No additional sense information
[ 1550.712092] sr1: CDROM (ioctl) error, command: Get configuration 46 00 00 00 00 00 00 00 20 00
[ 1550.712108] sr: Sense Key : Hardware Error [current]
[ 1550.712113] sr: Add. Sense: No additional sense information
[ 1551.127598] sr1: CDROM (ioctl) error, command: Get configuration 46 00 00 00 00 00 00 00 20 00
[ 1551.127615] sr: Sense Key : Hardware Error [current]
[ 1551.127620] sr: Add. Sense: No additional sense information
[ 1551.393619] sr1: CDROM (ioctl) error, command: Get configuration 46 00 00 00 00 00 00 00 20 00
[ 1551.393636] sr: Sense Key : Hardware Error [current]
[ 1551.393641] sr: Add. Sense: No additional sense information
[ 1551.770459] sr1: CDROM (ioctl) error, command: Get configuration 46 00 00 00 00 00 00 00 20 00
[ 1551.770475] sr: Sense Key : Hardware Error [current]
[ 1551.770480] sr: Add. Sense: No additional sense information
[ 1552.254995] sr1: CDROM (ioctl) error, command: Get configuration 46 00 00 00 00 00 00 00 20 00
[ 1552.255012] sr: Sense Key : Hardware Error [current]
[ 1552.255016] sr: Add. Sense: No additional sense information
[ 1612.989049] scsi 8:0:0:0: rejecting I/O to offline device
[ 1612.989470] scsi 8:0:0:0: rejecting I/O to dead device