Created attachment 763161 [details]
Upstream commit that resolves this issue

commit a6d13308ec0baca9a5bd48f80d02e5c71a54287f
Author: Jonathan Brassow <jbrassow@redhat.com>
Date:   Wed Jun 19 17:50:10 2013 -0500

    RAID/MIRROR: Honor mirror_segtype_default when upconverting linear LVs
    
    If the user would upconvert a linear LV to a mirror without specifying
    the segment type ("--type mirror" vs "--type raid1"), the "mirror"
    segment type would be chosen without consulting the 'default_mirror_segtype'
    setting in lvm.conf.  This is now used as the basis for determining
    which should be used if left unspecified.

Unfortunately, this does not seem to work:

[root@tardis-01 ~]# grep segtype /etc/lvm/lvm.conf
    # 'mirror_segtype_default' defines which segtype will be used when the
    mirror_segtype_default = "raid1"
    # 'raid10_segtype_default' determines the segment types used by default
    raid10_segtype_default = "mirror"
[root@tardis-01 ~]# lvcreate -n simple_lv mirror -L 250M
  Rounding up size to full physical extent 252.00 MiB
  Logical volume "simple_lv" created
[root@tardis-01 ~]# lvconvert -m1 mirror/simple_lv
  mirror/simple_lv: Converted: 0.0%
  mirror/simple_lv: Converted: 100.0%

[root@tardis-01 ~]# lvs -a mirror/simple_lv -o +segtype
  LV        VG     Attr       LSize   Pool Origin Data%  Move Log            Cpy%Sync Convert Type  
  simple_lv mirror mwi-a-m--- 252.00m                         simple_lv_mlog   100.00         mirror

Created attachment 786524 [details]
Verbose lvconvert

Some additional info:

[root@tardis-01 ~]# lvm dumpconfig --mergedconfig global
global {
	umask=63
	test=0
	units="h"
	si_unit_consistency=1
	activation=1
	proc="/proc"
	locking_type=1
	wait_for_locks=1
	fallback_to_clustered_locking=1
	fallback_to_local_locking=1
	locking_dir="/var/lock/lvm"
	prioritise_write_locks=1
	abort_on_internal_errors=0
	detect_internal_vg_cache_corruption=0
	metadata_read_only=0
	mirror_segtype_default="raid1"
	raid10_segtype_default="mirror"
	use_lvmetad=1
}

Why is this not triggered by the test suite?  These tests are in there:

FROM lvconvert-mirror.sh:
# convert from linear to 2-way mirror ("mirror" default type)
lvcreate -aey -l2 -n $lv1 $vg "$dev1"
lvconvert -i1 -m+1 $vg/$lv1 "$dev2" "$dev3:0-1" \
        --config 'global { mirror_segtype_default = "mirror" }'
lvs --noheadings -o attr $vg/$lv1 | grep '^m*'
lvremove -ff $vg

# convert from linear to 2-way mirror (override "raid1" default type)
lvcreate -aey -l2 -n $lv1 $vg "$dev1"
lvconvert -i1 --type mirror -m+1 $vg/$lv1 "$dev2" "$dev3:0-1" \
        --config 'global { mirror_segtype_default = "raid1" }'
lvs --noheadings -o attr $vg/$lv1 | grep '^m*'
lvremove -ff $vg


FROM lvconvert-raid.sh:
###########################################
# Linear to RAID1 conversion ("raid1" default segtype)
###########################################
lvcreate -aey -l 2 -n $lv1 $vg
lvconvert -m 1 $vg/$lv1 \
        --config 'global { mirror_segtype_default = "raid1" }'
lvs --noheadings -o attr $vg/$lv1 | grep '^r*'
lvremove -ff $vg

###########################################
# Linear to RAID1 conversion (override "mirror" default segtype)
###########################################
lvcreate -aey -l 2 -n $lv1 $vg
lvconvert --type raid1 -m 1 $vg/$lv1 \
        --config 'global { mirror_segtype_default = "mirror" }'
lvs --noheadings -o attr $vg/$lv1 | grep '^r*'
lvremove -ff $vg

It is the '*' in the grep expression - they are matching no matter what.

Changing:
lvs --noheadings -o attr $vg/$lv1 | grep '^r*'
to
lvs --noheadings -o attr $vg/$lv1 | grep '^r'

will fix the tests...

code and tests fixed in upstream commit:

commit 098896fb2905cd02d02b7271be489e32d86c073d
Author: Jonathan Brassow <jbrassow@redhat.com>
Date:   Wed Sep 25 22:25:43 2013 -0500

    mirror/RAID: Honor mirror_segtype_default when converting from linear
    
    1) When converting from an x-way mirror/raid1 to a y-way mirror/raid1,
    the default behaviour should be to stay the same segment type.
    
    2) When converting from linear to mirror or raid1, the default behaviour
    should honor the mirror_segtype_default.
    
    3) When converting and the '--type' argument is specified, the '--type'
    argument should be honored.
    
    catch such conditions, but errors in the tests caused the issue to go
    unnoticed.  The code has been fixed to perform #2 properly, the tests
    have been corrected to properly test for #2, and a few other tests
    were changed to explicitly specify the '--type mirror' when necessary.

[root@virt-013 yum.repos.d]# lvcreate -L1G -n linear vg
  Logical volume "linear" created

[root@virt-013 yum.repos.d]# lvconvert -m1 vg/linear

[root@virt-013 yum.repos.d]# lvs -o+segtype
  LV      VG         Attr       LSize   Pool Origin Data%  Move Log Cpy%Sync Convert Type  
  linear  vg         rwi-a-r---   1.00g                                18.75         raid1 


Marking verified with: lvm2-2.02.100-4.el6.x86_64

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