Bug 619221

This issue has been proposed when we are only considering blocker
issues in the current Red Hat Enterprise Linux release.

** If you would still like this issue considered for the current
release, ask your support representative to file as a blocker on
your behalf. Otherwise ask that it be considered for the next
Red Hat Enterprise Linux release. **

FYI: this issue was introduced by the following patch.

Fix reversal of LV list before performing a split mirror.
https://www.redhat.com/archives/lvm-devel/2010-July/msg00122.html

With this patch, PVs lists (lp->pvh) are not used when a mirror is split (lp->keep_images != 0) and work as if no PVs are specified in the command line. Therefore, lvconvert doesn't split off specified devices even if devices assigned to a mirror leg are requested.

This is an example.

vg00-lv00 (253:3)
 |-vg00-lv00_mimage_1 (253:2)
 |  `- (8:32)　　　　　　　　　　　　<== /dev/sdb
 |-vg00-lv00_mimage_0 (253:1)
 |  `- (8:16)                     <== /dev/sdc
 `-vg00-lv00_mlog (253:0)
    `- (8:48)                     <== /dev/sdd

# lvconvert --mirrorlog disk --splitmirrors 1 --name new vg00/lv00 /dev/sdb
  Logical volume lv00 converted.

# dmsetup ls --tree -o ascii
vg00-new (253:2)
 `- (8:32)                        <== /dev/sdc is removed instead of /dev/sdb
vg00-lv00 (253:3)
 `- (8:16)

I read the description of the patch, but I couldn't get how this patch works.
I appreciate Jon's explanation.

The problem is worse than the subject implies.  All PVs specified on the command line are ignored when performing a split mirror operation.

So, in the case where you specify the log device, it is ignored and the last sub-lv is taken ([split_log_mimage_1]).  If you would have specified a valid device, it too would have been ignored and just chosen whatever devices are associated with the highest number mimage's.

Patch awaiting upstream review.

Fix checked-in upstream.

[root@taft-02 ~]# lvs -a -o +devices
  LV                   VG        Attr   LSize   Log            Copy%  Devices
  split_log            taft      mwi-a- 300.00m split_log_mlog 100.00 split_log_mimage_0(0),split_log_mimage_1(0)
  [split_log_mimage_0] taft      iwi-ao 300.00m                       /dev/sdb1(0)
  [split_log_mimage_1] taft      iwi-ao 300.00m                       /dev/sdc1(0)
  [split_log_mlog]     taft      lwi-ao   4.00m                       /dev/sdh1(0)

[root@taft-02 ~]# lvconvert --splitmirrors 1 --name new taft/split_log /dev/sdh1
  Insufficient removable PVs given to satisfy request

Fix verified in latest rpms.

2.6.32-59.1.el6.x86_64

lvm2-2.02.72-7.el6    BUILT: Wed Aug 11 17:12:24 CDT 2010
lvm2-libs-2.02.72-7.el6    BUILT: Wed Aug 11 17:12:24 CDT 2010
lvm2-cluster-2.02.72-7.el6    BUILT: Wed Aug 11 17:12:24 CDT 2010
udev-147-2.22.el6    BUILT: Fri Jul 23 07:21:33 CDT 2010
device-mapper-1.02.53-7.el6    BUILT: Wed Aug 11 17:12:24 CDT 2010
device-mapper-libs-1.02.53-7.el6    BUILT: Wed Aug 11 17:12:24 CDT 2010
device-mapper-event-1.02.53-7.el6    BUILT: Wed Aug 11 17:12:24 CDT 2010
device-mapper-event-libs-1.02.53-7.el6    BUILT: Wed Aug 11 17:12:24 CDT 2010
cmirror-2.02.72-7.el6    BUILT: Wed Aug 11 17:12:24 CDT 2010

Red Hat Enterprise Linux 6.0 is now available and should resolve
the problem described in this bug report. This report is therefore being closed
with a resolution of CURRENTRELEASE. You may reopen this bug report if the
solution does not work for you.