In udev, what kind of device events match ACTION==“change”?
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The udev rules I've created so far only deal with devices being added or removed, i.e.:
ACTION=="add"... or ACTION=="remove"...
I've come across an example of a rule that seems to deal with device state changes as well:
ACTION=="add|change", KERNEL=="sd[b-z]", ATTRqueue/rotational=="1", RUN+="/usr/bin/hdparm -B 127 -S 12 /dev/%k"
I take it that the above rule applies whenever a matching device is added OR its state changes.
Question: What kind of state changes are possible (generally and specific to a USB hard drive)?
I've checked all udev documentation I can find and there's barely any mention of, or usage guidance, in respect of device state changes or specifically ACTION="change".
udev devices
asked Nov 2 '15 at 20:45
misha256misha256
2021212
add a comment |
The udev rules I've created so far only deal with devices being added or removed, i.e.:
ACTION=="add"... or ACTION=="remove"...
I've come across an example of a rule that seems to deal with device state changes as well:
ACTION=="add|change", KERNEL=="sd[b-z]", ATTRqueue/rotational=="1", RUN+="/usr/bin/hdparm -B 127 -S 12 /dev/%k"
I take it that the above rule applies whenever a matching device is added OR its state changes.
Question: What kind of state changes are possible (generally and specific to a USB hard drive)?
I've checked all udev documentation I can find and there's barely any mention of, or usage guidance, in respect of device state changes or specifically ACTION="change".
udev devices
asked Nov 2 '15 at 20:45
misha256misha256
2021212
add a comment |
The udev rules I've created so far only deal with devices being added or removed, i.e.:
ACTION=="add"... or ACTION=="remove"...
I've come across an example of a rule that seems to deal with device state changes as well:
ACTION=="add|change", KERNEL=="sd[b-z]", ATTRqueue/rotational=="1", RUN+="/usr/bin/hdparm -B 127 -S 12 /dev/%k"
I take it that the above rule applies whenever a matching device is added OR its state changes.
Question: What kind of state changes are possible (generally and specific to a USB hard drive)?
I've checked all udev documentation I can find and there's barely any mention of, or usage guidance, in respect of device state changes or specifically ACTION="change".
udev devices
asked Nov 2 '15 at 20:45
misha256misha256
2021212
The udev rules I've created so far only deal with devices being added or removed, i.e.:
ACTION=="add"... or ACTION=="remove"...
I've come across an example of a rule that seems to deal with device state changes as well:
ACTION=="add|change", KERNEL=="sd[b-z]", ATTRqueue/rotational=="1", RUN+="/usr/bin/hdparm -B 127 -S 12 /dev/%k"
I take it that the above rule applies whenever a matching device is added OR its state changes.
Question: What kind of state changes are possible (generally and specific to a USB hard drive)?
I've checked all udev documentation I can find and there's barely any mention of, or usage guidance, in respect of device state changes or specifically ACTION="change".
udev devices
udev devices
asked Nov 2 '15 at 20:45
misha256misha256
2021212
asked Nov 2 '15 at 20:45
misha256misha256
2021212
edited Nov 2 '15 at 23:42
misha256
asked Nov 2 '15 at 20:45
misha256misha256
2021212
asked Nov 2 '15 at 20:45
misha256misha256
2021212
asked Nov 2 '15 at 20:45
misha256misha256
2021212
2021212
add a comment |
add a comment |
2 Answers
2
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oldest
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"change" corresponds, for example, to removing or inserting an sdcard in a sdcard reader, or changing the hard disc inside a usb-to-sata enclosure. The device itself is not added nor removed, but the media is no longer the same.
answered Nov 3 '15 at 9:19
meuhmeuh
31.9k11954
add a comment |
udev change event gets triggered when media changer (regards to tape - Netbackup like environment) or sd card reader is used in continuation with different media or sd card. When a same device is re-added (a san disk is re-added again or you do switchdisable/enable on the switch side or target port disable/enable from target side )
Below are the few change udev events that we see on the host side, when I did target port disable (from Vexata VX100 array) for an existing san lun
KERNEL[34942.047543] change /devices/virtual/block/dm-0 (block)
KERNEL[34942.047596] change /devices/virtual/block/dm-1 (block)
KERNEL[34942.047613] change /devices/virtual/block/dm-2 (block)
KERNEL[34942.047631] change /devices/virtual/block/dm-3 (block)
KERNEL[34942.047678] change /devices/virtual/block/dm-4 (block)
UDEV [34942.053448] change /devices/virtual/block/dm-3 (block)
UDEV [34942.053486] change /devices/virtual/block/dm-4 (block)
UDEV [34942.053507] change /devices/virtual/block/dm-0 (block)
UDEV [34942.053536] change /devices/virtual/block/dm-2 (block)
answered Jan 17 at 13:11
Venfah NazirVenfah Nazir
112
add a comment |
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2 Answers
2
active
oldest
votes
2 Answers
2
active
oldest
votes
active
oldest
votes
active
oldest
votes
"change" corresponds, for example, to removing or inserting an sdcard in a sdcard reader, or changing the hard disc inside a usb-to-sata enclosure. The device itself is not added nor removed, but the media is no longer the same.
answered Nov 3 '15 at 9:19
meuhmeuh
31.9k11954
add a comment |
"change" corresponds, for example, to removing or inserting an sdcard in a sdcard reader, or changing the hard disc inside a usb-to-sata enclosure. The device itself is not added nor removed, but the media is no longer the same.
answered Nov 3 '15 at 9:19
meuhmeuh
31.9k11954
add a comment |
"change" corresponds, for example, to removing or inserting an sdcard in a sdcard reader, or changing the hard disc inside a usb-to-sata enclosure. The device itself is not added nor removed, but the media is no longer the same.
answered Nov 3 '15 at 9:19
meuhmeuh
31.9k11954
"change" corresponds, for example, to removing or inserting an sdcard in a sdcard reader, or changing the hard disc inside a usb-to-sata enclosure. The device itself is not added nor removed, but the media is no longer the same.
answered Nov 3 '15 at 9:19
meuhmeuh
31.9k11954
answered Nov 3 '15 at 9:19
meuhmeuh
31.9k11954
answered Nov 3 '15 at 9:19
meuhmeuh
31.9k11954
answered Nov 3 '15 at 9:19
meuhmeuh
31.9k11954
31.9k11954
add a comment |
add a comment |
udev change event gets triggered when media changer (regards to tape - Netbackup like environment) or sd card reader is used in continuation with different media or sd card. When a same device is re-added (a san disk is re-added again or you do switchdisable/enable on the switch side or target port disable/enable from target side )
Below are the few change udev events that we see on the host side, when I did target port disable (from Vexata VX100 array) for an existing san lun
KERNEL[34942.047543] change /devices/virtual/block/dm-0 (block)
KERNEL[34942.047596] change /devices/virtual/block/dm-1 (block)
KERNEL[34942.047613] change /devices/virtual/block/dm-2 (block)
KERNEL[34942.047631] change /devices/virtual/block/dm-3 (block)
KERNEL[34942.047678] change /devices/virtual/block/dm-4 (block)
UDEV [34942.053448] change /devices/virtual/block/dm-3 (block)
UDEV [34942.053486] change /devices/virtual/block/dm-4 (block)
UDEV [34942.053507] change /devices/virtual/block/dm-0 (block)
UDEV [34942.053536] change /devices/virtual/block/dm-2 (block)
answered Jan 17 at 13:11
Venfah NazirVenfah Nazir
112
add a comment |
udev change event gets triggered when media changer (regards to tape - Netbackup like environment) or sd card reader is used in continuation with different media or sd card. When a same device is re-added (a san disk is re-added again or you do switchdisable/enable on the switch side or target port disable/enable from target side )
Below are the few change udev events that we see on the host side, when I did target port disable (from Vexata VX100 array) for an existing san lun
KERNEL[34942.047543] change /devices/virtual/block/dm-0 (block)
KERNEL[34942.047596] change /devices/virtual/block/dm-1 (block)
KERNEL[34942.047613] change /devices/virtual/block/dm-2 (block)
KERNEL[34942.047631] change /devices/virtual/block/dm-3 (block)
KERNEL[34942.047678] change /devices/virtual/block/dm-4 (block)
UDEV [34942.053448] change /devices/virtual/block/dm-3 (block)
UDEV [34942.053486] change /devices/virtual/block/dm-4 (block)
UDEV [34942.053507] change /devices/virtual/block/dm-0 (block)
UDEV [34942.053536] change /devices/virtual/block/dm-2 (block)
answered Jan 17 at 13:11
Venfah NazirVenfah Nazir
112
add a comment |
udev change event gets triggered when media changer (regards to tape - Netbackup like environment) or sd card reader is used in continuation with different media or sd card. When a same device is re-added (a san disk is re-added again or you do switchdisable/enable on the switch side or target port disable/enable from target side )
Below are the few change udev events that we see on the host side, when I did target port disable (from Vexata VX100 array) for an existing san lun
KERNEL[34942.047543] change /devices/virtual/block/dm-0 (block)
KERNEL[34942.047596] change /devices/virtual/block/dm-1 (block)
KERNEL[34942.047613] change /devices/virtual/block/dm-2 (block)
KERNEL[34942.047631] change /devices/virtual/block/dm-3 (block)
KERNEL[34942.047678] change /devices/virtual/block/dm-4 (block)
UDEV [34942.053448] change /devices/virtual/block/dm-3 (block)
UDEV [34942.053486] change /devices/virtual/block/dm-4 (block)
UDEV [34942.053507] change /devices/virtual/block/dm-0 (block)
UDEV [34942.053536] change /devices/virtual/block/dm-2 (block)
answered Jan 17 at 13:11
Venfah NazirVenfah Nazir
112
udev change event gets triggered when media changer (regards to tape - Netbackup like environment) or sd card reader is used in continuation with different media or sd card. When a same device is re-added (a san disk is re-added again or you do switchdisable/enable on the switch side or target port disable/enable from target side )
Below are the few change udev events that we see on the host side, when I did target port disable (from Vexata VX100 array) for an existing san lun
KERNEL[34942.047543] change /devices/virtual/block/dm-0 (block)
KERNEL[34942.047596] change /devices/virtual/block/dm-1 (block)
KERNEL[34942.047613] change /devices/virtual/block/dm-2 (block)
KERNEL[34942.047631] change /devices/virtual/block/dm-3 (block)
KERNEL[34942.047678] change /devices/virtual/block/dm-4 (block)
UDEV [34942.053448] change /devices/virtual/block/dm-3 (block)
UDEV [34942.053486] change /devices/virtual/block/dm-4 (block)
UDEV [34942.053507] change /devices/virtual/block/dm-0 (block)
UDEV [34942.053536] change /devices/virtual/block/dm-2 (block)
answered Jan 17 at 13:11
Venfah NazirVenfah Nazir
112
answered Jan 17 at 13:11
Venfah NazirVenfah Nazir
112
answered Jan 17 at 13:11
Venfah NazirVenfah Nazir
112
answered Jan 17 at 13:11
Venfah NazirVenfah Nazir
112
112
add a comment |
add a comment |
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