[dm-devel] 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 at 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