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I'm running Ubuntu 11.04, with the / partition in an encrypted LVM volume. /home is in the same logical volume. I'm trying to use the LVM snapshot functionality to enable time-consistent backups of the running system.

I left over 500MB of unpartitioned space in the volume group, as I understand it needs that empty space for snapshot data. Whenever I try to create a snapshot, this is what happens:

$ sudo lvscan
  ACTIVE          '/dev/vgroup1/volume1' [10.62 GiB] inherit

$ sudo lvcreate -L400M -s -n snapit /dev/vgroup1/volume1
      The link /dev/vgroup1/snapit should had been created by udev but it was not found. Falling back to direct link creation.
      semid 589825: semop failed for cookie 0xd4d5c76: incorrect semaphore state
      Failed to set a proper state for notification semaphore identified by cookie value 223173750 (0xd4d5c76) to initialize waiting for incoming notifications.
      Logical volume "snapit" created

What am I doing wrong? Or is this an Ubuntu bug?

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It could be related to this bug... – Mike Rowave Sep 13 '11 at 15:56
The snapshot seemed to work despite that error, but I am concerned about its integrity given the error. I'd prefer to eliminate that error if possible. – Mike Rowave Sep 18 '11 at 16:06
up vote 0 down vote accepted

The error didn't happen when using the LVM GUI.

Upgrading to a newer kernel eliminated it altogether.

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