Both media-change events generated by kernel appears during one cycle.
Once I need to use the reader, I found kernel does not signal insertion of a medium, I had to manually rescan partion table with blockdev --rereadpt. These spurious periodic media events could be a work-around implemented in kernel for the special hardware.
The kernel messages correlate with following kernel/udev events:
KERNEL[684.511147] change /devices/ pci0000: 00/0000: 00:0e.5/ usb4/4- 1/4-1:1. 0/host2/ target2: 0:0/2:0: 0:0/block/ sdb (block) /devices/ pci0000: 00/0000: 00:0e.5/ usb4/4- 1/4-1:1. 0/host2/ target2: 0:0/2:0: 0:0/block/ sdb
ACTION=change
DEVNAME=/dev/sdb
DEVPATH=
DEVTYPE=disk
DISK_MEDIA_CHANGE=1
MAJOR=8
MINOR=16
SEQNUM=725
SUBSYSTEM=block
UDEV [684.602048] change /devices/ pci0000: 00/0000: 00:0e.5/ usb4/4- 1/4-1:1. 0/host2/ target2: 0:0/2:0: 0:0/block/ sdb (block) /dev/disk/ by-id/usb- Generic- _Multi- Card_2007111417 3400000- 0:0 /dev/disk/ by-path/ pci-0000: 00:0e.5- usb-0:1: 1.0-scsi- 0:0:0:0 /devices/ pci0000: 00/0000: 00:0e.5/ usb4/4- 1/4-1:1. 0/host2/ target2: 0:0/2:0: 0:0/block/ sdb ENC=Multi- Card\x20\ x20\x20\ x20\x20\ x20 pci-0000: 00:0e.5- usb-0:1: 1.0-scsi- 0:0:0:0 TAG=pci- 0000_00_ 0e_5-usb- 0_1_1_0- scsi-0_ 0_0_0 Generic- _Multi- Card_2007111417 3400000- 0:0 SHORT=200711141 73400000 DRIVER= ums-realtek INTERFACES= :080650: INTERFACE_ NUM=00 ENC=Generic- D=10909217
ACTION=change
DEVLINKS=
DEVNAME=/dev/sdb
DEVPATH=
DEVTYPE=disk
DISK_MEDIA_CHANGE=1
ID_BUS=usb
ID_INSTANCE=0:0
ID_MODEL=Multi-Card
ID_MODEL_
ID_MODEL_ID=0158
ID_PATH=
ID_PATH_
ID_REVISION=1.00
ID_SERIAL=
ID_SERIAL_
ID_TYPE=disk
ID_USB_
ID_USB_
ID_USB_
ID_VENDOR=Generic-
ID_VENDOR_
ID_VENDOR_ID=0bda
MAJOR=8
MINOR=16
SEQNUM=725
SUBSYSTEM=block
USEC_INITIALIZE
KERNEL[687.073016] change /devices/ pci0000: 00/0000: 00:0e.5/ usb4/4- 1/4-1:1. 0/host2/ target2: 0:0/2:0: 0:0/block/ sdb (block) /devices/ pci0000: 00/0000: 00:0e.5/ usb4/4- 1/4-1:1. 0/host2/ target2: 0:0/2:0: 0:0/block/ sdb
ACTION=change
DEVNAME=/dev/sdb
DEVPATH=
DEVTYPE=disk
DISK_MEDIA_CHANGE=1
MAJOR=8
MINOR=16
SEQNUM=726
SUBSYSTEM=block
UDEV [687.089178] change /devices/ pci0000: 00/0000: 00:0e.5/ usb4/4- 1/4-1:1. 0/host2/ target2: 0:0/2:0: 0:0/block/ sdb (block) /dev/disk/ by-id/usb- Generic- _Multi- Card_2007111417 3400000- 0:0 /dev/disk/ by-path/ pci-0000: 00:0e.5- usb-0:1: 1.0-scsi- 0:0:0:0 /devices/ pci0000: 00/0000: 00:0e.5/ usb4/4- 1/4-1:1. 0/host2/ target2: 0:0/2:0: 0:0/block/ sdb ENC=Multi- Card\x20\ x20\x20\ x20\x20\ x20 pci-0000: 00:0e.5- usb-0:1: 1.0-scsi- 0:0:0:0 TAG=pci- 0000_00_ 0e_5-usb- 0_1_1_0- scsi-0_ 0_0_0 Generic- _Multi- Card_2007111417 3400000- 0:0 SHORT=200711141 73400000 DRIVER= ums-realtek INTERFACES= :080650: INTERFACE_ NUM=00 ENC=Generic- D=10909217
ACTION=change
DEVLINKS=
DEVNAME=/dev/sdb
DEVPATH=
DEVTYPE=disk
DISK_MEDIA_CHANGE=1
ID_BUS=usb
ID_INSTANCE=0:0
ID_MODEL=Multi-Card
ID_MODEL_
ID_MODEL_ID=0158
ID_PATH=
ID_PATH_
ID_REVISION=1.00
ID_SERIAL=
ID_SERIAL_
ID_TYPE=disk
ID_USB_
ID_USB_
ID_USB_
ID_VENDOR=Generic-
ID_VENDOR_
ID_VENDOR_ID=0bda
MAJOR=8
MINOR=16
SEQNUM=726
SUBSYSTEM=block
USEC_INITIALIZE
Both media-change events generated by kernel appears during one cycle.
Once I need to use the reader, I found kernel does not signal insertion of a medium, I had to manually rescan partion table with blockdev --rereadpt. These spurious periodic media events could be a work-around implemented in kernel for the special hardware.