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Description of problem:
Can not create thin snapshots when pool is created with --zero n.

Version-Release number of selected component (if applicable):
lvm2-2.02.99-0.367.el6_4.x86_64 (upstream)

How reproducible:
100%

Steps to Reproduce:

    #!/bin/bash
    VG=vg
    POOL=pool
    ORIGIN=origin
    SNAP=snap
    
    OPTS="--zero n"
    
    lvcreate --thin -L 2G $OPTS ${VG}/${POOL}
    lvcreate --virtualsize 500M --thinpool ${VG}/${POOL} -n ${ORIGIN}
    lvcreate -s /dev/${VG}/${ORIGIN} -n ${SNAP} -vvvv &> lvcreate-s-failed.$(date "+%Y%m%d-%H%M%S").out

Actual results:
Last lvcreate fails as snap device is not activated and can not be written to:
    /dev/vg/snap: not found: device not cleared
    Aborting. Failed to wipe snapshot exception store.

Expected results:
Pass

Additional info:

Fixed regression introduced in 2.02.94 upstream with:
https://www.redhat.com/archives/lvm-devel/2013-July/msg00210.html


Using snapshots on non-zeroed thin pool lead to cleared 4KB header of such snapshot.

Verified with:

lvm2-2.02.100-1.el6.x86_64



 #!/bin/bash
    VG=vg
    POOL=pool
    ORIGIN=origin
    SNAP=snap
    
    OPTS="--zero n"
    
    lvcreate --thin -L 2G $OPTS ${VG}/${POOL}
    lvcreate --virtualsize 500M --thinpool ${VG}/${POOL} -n ${ORIGIN}
    lvcreate -s /dev/${VG}/${ORIGIN} -n ${SNAP} -vvvv &> lvcreate-s-failed.$(date "+%Y%m%d-%H%M%S").out

Executed script:

Logical volume "lvol0" created
Logical volume "pool" created
Logical volume "origin" created

Since the problem described in this bug report should be
resolved in a recent advisory, it has been closed with a
resolution of ERRATA.

For information on the advisory, and where to find the updated
files, follow the link below.

If the solution does not work for you, open a new bug report.

http://rhn.redhat.com/errata/RHBA-2013-1704.html