lvremove returns Unable to deactivate open logical volume

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Environment

SUSE Linux Enterprise Server 11 Service Pack 2 (SLES 11 SP2)
SUSE Linux Enterprise Server 11 Service Pack 3 (SLES 11 SP3)

Situation

'lvremove' is run to remove an unmounted LVM logical volume
snapshot and returns an error indicating that the snapshot is
still open:

# lvremove vg-mylvsnapshot
Unable to deactivate open vg-mylvsnapshot (253:13)
Failed to resume mylvsnapshot.
libdevmapper exiting with 1 device(s) still suspended.

Resolution

Periodically check the output of the 'dmsetup info' command for this snapshot
and retry once the open count is zero.

In the example below, the open count is 2:

# dmsetup info vg-mylvsnapshot
Name:              vg-mylvsnapshot
State:             ACTIVE
Read Ahead:        1024
Tables present:    LIVE
Open count:        2
Event number:      0
Major, minor:      253, 13
Number of targets: 1
UUID: LVM-spdA9rfc0Wc9wUMJVGQ2S8h3RZqErkVOUDwaH6S9LDjTR4ojEUFuBS66005ARP3D-mylvsnapshot

In this example, the open count is zero:

# dmsetup info vg-mylvsnapshot
Name:              vg-mylvsnapshot
State:             ACTIVE
Read Ahead:        1024
Tables present:    LIVE
Open count:        0
Event number:      0
Major, minor:      253, 13
Number of targets: 1
UUID: LVM-spdA9rfc0Wc9wUMJVGQ2S8h3RZqErkVOUDwaH6S9LDjTR4ojEUFuBS66005ARP3D-mylvsnapshot

The snapshot cannot be removed until the open count is zero.

Cause

The snapshot is still considered in use until the open count reaches zero.

This condition is most frequently reported when a script is used to automate
the unmount and lvmremove process for a snapshot.

It's caused by a delay between the time that the snapshot is unmounted and
when the open count reaches zero.

In most cases, this delay is within a few seconds.

Disclaimer

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