Bug 805425

Summary: [RFE] Add dmeventd option to list currently monitored devices
Product: [Fedora] Fedora Reporter: Peter Rajnoha <prajnoha>
Component: lvm2Assignee: LVM and device-mapper development team <lvm-team>
Status: NEW --- QA Contact: Fedora Extras Quality Assurance <extras-qa>
Severity: low Docs Contact:
Priority: low    
Version: rawhideCC: agk, bmarzins, bmr, dwysocha, heinzm, jonathan, lvm-team, msnitzer, prajnoha, zkabelac
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Hardware: All   
OS: Linux   
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Description Peter Rajnoha 2012-03-21 09:31:12 UTC 
There's already a tool that lists currently monitored devices, the "dmevent_tool" that is a part of the "dmraid" package. So we should probably consider moving this functionality from dmraid to device-mapper-event.

It needs looking at a bit though since it doesn't show the correct information, e.g. for lvol0 as origin and it's snapshot lvol1:

The syslog says:
  Mar 21 10:18:12 devel lvm[14992]: Monitoring snapshot vg-lvol1

However, the dmevent_tool says:

[0] devel/~ # dmevent_tool -mr
[0] devel/~ # dmevent_tool -mu
vg-lvol1 not monitored
vg-lvol0 not monitored
vg-lvol0-real not monitored
vg-lvol1-cow not monitored

Monitoring and unmonitoring devices on demand would be fine as well (which is already supposed to be done by the dmevent_tool).

All this functionality would help with debugging dmeventd related problems then.
Comment 1 Alasdair Kergon 2012-07-11 12:47:21 UTC 
Currently:

dmeventd [-d [-d [-d]]] [-f] [-h] [-R] [-V] [-?]

   -d       Log debug messages to syslog (-d, -dd, -ddd)
   -f       Don't fork, run in the foreground
   -h -?    Show this help information
   -R       Restart dmeventd
   -V       Show version of dmeventd


dmevent_tool -[Vh?amru]

   -V      Show version of dmevent_tool

   -{h/?}  Show this help information

   -m[r|u] List all currently active device mapper devices
           and their current status with dmeventd
           for registered (-r)/unregistered (-m) devices
             Syntax: dmevent_tool -m[u|r]

   -a[r|u] Same as -m, but for devices with UUID only!
             Syntax: dmevent_tool -a[u|r]

   -r      Register a device with dmeventd
             Syntax: dmevent_tool -r <device name> <path to DSO library>
             Example: dmevent_tool -r isw_abcdeh_Volume0 libdmraid-events.so

   -u      Unregister a device with dmeventd
             Syntax: dmevent_tool -u <device name> [<path to DSO library>]
             Example: dmevent_tool -u isw_abcdefgh_Volume0
Comment 2 Alasdair Kergon 2012-07-11 12:50:05 UTC 
The whole client library functionality should be exposed to the command line.
Comments in the header file suggest it's waiting for some review.