In udev, what kind of device events match ACTION==“change”?
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]", ATTR{queue/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
192211
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]", ATTR{queue/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
192211
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]", ATTR{queue/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
192211
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]", ATTR{queue/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
192211
asked Nov 2 '15 at 20:45
misha256misha256
192211
edited Nov 2 '15 at 23:42
misha256
asked Nov 2 '15 at 20:45
misha256misha256
192211
asked Nov 2 '15 at 20:45
misha256misha256
192211
asked Nov 2 '15 at 20:45
misha256misha256
192211
192211
add a comment |
add a comment |
2 Answers
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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
31.8k11854
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 13 hours ago
Venfah NazirVenfah Nazir
112
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2 Answers
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2 Answers
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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
31.8k11854
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
31.8k11854
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
31.8k11854
"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
31.8k11854
answered Nov 3 '15 at 9:19
meuhmeuh
31.8k11854
answered Nov 3 '15 at 9:19
meuhmeuh
31.8k11854
answered Nov 3 '15 at 9:19
meuhmeuh
31.8k11854
31.8k11854
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 13 hours ago
Venfah NazirVenfah Nazir
112
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Venfah Nazir is a new contributor to this site. Take care in asking for clarification, commenting, and answering.
Check out our Code of Conduct.
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 13 hours ago
Venfah NazirVenfah Nazir
112
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Venfah Nazir is a new contributor to this site. Take care in asking for clarification, commenting, and answering.
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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 13 hours ago
Venfah NazirVenfah Nazir
112
New contributor
Venfah Nazir is a new contributor to this site. Take care in asking for clarification, commenting, and answering.
Check out our Code of Conduct.
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 13 hours ago
Venfah NazirVenfah Nazir
112
New contributor
Venfah Nazir is a new contributor to this site. Take care in asking for clarification, commenting, and answering.
Check out our Code of Conduct.
answered 13 hours ago
Venfah NazirVenfah Nazir
112
New contributor
Venfah Nazir is a new contributor to this site. Take care in asking for clarification, commenting, and answering.
Check out our Code of Conduct.
answered 13 hours ago
Venfah NazirVenfah Nazir
112
answered 13 hours ago
Venfah NazirVenfah Nazir
112
112
New contributor
Venfah Nazir is a new contributor to this site. Take care in asking for clarification, commenting, and answering.
Check out our Code of Conduct.
New contributor
Venfah Nazir is a new contributor to this site. Take care in asking for clarification, commenting, and answering.
Check out our Code of Conduct.
Venfah Nazir is a new contributor to this site. Take care in asking for clarification, commenting, and answering.
Check out our Code of Conduct.
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