Resetting dmsetup open count

Resetting dmsetup open count

[Peter Lavin]

Dear dmsetup mailers,

I am attempting to remove a LVM in CentOS 5. I am getting the following 
message...

Can't remove open logical volume "lvm_name"

I can delete the link... /dev/vg01/lvm_name and also delete the 
associated block... /dev/mapper/vg01-lvm_name.

However, when I attempt to recreate the LVM using the same name (I need 
to use the same name). I get a message that the LVM already exists. I 
have traced this to dmsetup, where running dmsetup info vg01-lvm_name 
reveals...

[root@tg26 mapper]# dmsetup info vg01-lvm_name
Name: vg01-lvm_name
State: ACTIVE
Tables present: LIVE
Open count: 1  <------- this appears to be the problem
Event number: 0
Major, minor: 253, 63
Number of targets: 1
UUID: LVM-CT2Hz7dN6TLC3c8DydQ8nIenwjSmA8CI1yrsTLQy7Ip1Cxetz3 JrdQArvsgBqDsj

I may be able to reset this Open count by rebooting the machine but this 
is the least preferred option. Is there a was of resetting this 'Open 
count' in the dmsetup records without rebooting the system. My dmsetup 
version is pre- 4.8.0 so I cannot use the lvmremove -f option.

Peter

-- 
best regards,
Peter Lavin,
Computer Architecture & Grid Research Group,
Lloyd Institute, 005,
Trinity College Dublin, Ireland.
+353 1 8961536

Re: Resetting dmsetup open count

[Konrad Rzeszutek]

On Wed, Jul 02, 2008 at 04:39:25PM +0100, Peter Lavin wrote:
> Dear dmsetup mailers,
>
> I am attempting to remove a LVM in CentOS 5. I am getting the following 
> message...
>
> Can't remove open logical volume "lvm_name"
>
> I can delete the link... /dev/vg01/lvm_name and also delete the associated 
> block... /dev/mapper/vg01-lvm_name.
>
> However, when I attempt to recreate the LVM using the same name (I need to 
> use the same name). I get a message that the LVM already exists. I have 
> traced this to dmsetup, where running dmsetup info vg01-lvm_name reveals...
>
> [root@tg26 mapper]# dmsetup info vg01-lvm_name
> Name: vg01-lvm_name
> State: ACTIVE
> Tables present: LIVE
> Open count: 1  <------- this appears to be the problem
> Event number: 0
> Major, minor: 253, 63
> Number of targets: 1
> UUID: LVM-CT2Hz7dN6TLC3c8DydQ8nIenwjSmA8CI1yrsTLQy7Ip1Cxetz3 JrdQArvsgBqDsj
>
> I may be able to reset this Open count by rebooting the machine but this is 
> the least preferred option. Is there a was of resetting this 'Open count' 
> in the dmsetup records without rebooting the system. My dmsetup version is 
> pre- 4.8.0 so I cannot use the lvmremove -f option.

Did you use 'vgchange --available ln vg01-lvm_name' before trying to
remove it using 'dmsetup' ?