Hi Peter, thanks for reopening, sorry about lack of response on the original report. Can you provide:

1) sudo virsh pool-dumpxml $poolname   (for every logical pool)
2) sudo vgs
3) sudo lvs

libvirt is actually running the following command

lvs --separator , --noheadings --units b --unbuffered --nosuffix --options lv_name,origin,uuid,devices,seg_size,vg_extent_size $SOURCENAME

where $SOURCENAME is <source name="$SOURCENAME"/> from the dumpxml output. Could you try that as well?

Well, it's a bit different now. I'm using F17 now and it seems to be working there...

However, I still have F16 set up in a virt machine, so I tried to install virt-manager and stuff (just storage to test for the error - as that would be virt under virt, I expect that has no influence here). Now, I end up with *different* error message with current F16 updated version:

When trying to create a new pool out of existing VG with a mirror volume:
=========================================================================

Error creating pool: Could not start storage pool: cannot open volume '/dev/vg/lvol0,': No such file or directory

Traceback (most recent call last):
  File "/usr/share/virt-manager/virtManager/asyncjob.py", line 45, in cb_wrapper
    callback(asyncjob, *args, **kwargs)
  File "/usr/share/virt-manager/virtManager/createpool.py", line 482, in _async_pool_create
    poolobj = self._pool.install(create=True, meter=meter, build=build)
  File "/usr/lib/python2.7/site-packages/virtinst/Storage.py", line 744, in install
    build=build, autostart=False)
  File "/usr/lib/python2.7/site-packages/virtinst/Storage.py", line 489, in install
    raise RuntimeError(errmsg)
RuntimeError: Could not start storage pool: cannot open volume '/dev/vg/lvol0,': No such file or directory


Also when trying to refresh an existing pool where the mirror volume has been added:
===============================================================================

Error refreshing pool 'vg': cannot open volume '/dev/vg/lvol1,': No such file or directory

Traceback (most recent call last):
  File "/usr/share/virt-manager/virtManager/asyncjob.py", line 45, in cb_wrapper
    callback(asyncjob, *args, **kwargs)
  File "/usr/share/virt-manager/virtManager/asyncjob.py", line 66, in tmpcb
    callback(*args, **kwargs)
  File "/usr/share/virt-manager/virtManager/host.py", line 647, in cb
    pool.refresh()
  File "/usr/share/virt-manager/virtManager/storagepool.py", line 115, in refresh
    self.pool.refresh(0)
  File "/usr/lib64/python2.7/site-packages/libvirt.py", line 1832, in refresh
    if ret == -1: raise libvirtError ('virStoragePoolRefresh() failed', pool=self)
libvirtError: cannot open volume '/dev/vg/lvol1,': No such file or directory


All the LVs in that VG are deactivated then. The only problem appears in F16, F17 is already fine, so it must have been resolved just recently. Has anything changed with respect to LVM handling in between these releases?

(In reply to comment #2)
> Error creating pool: Could not start storage pool: cannot open volume
> '/dev/vg/lvol0,': No such file or directory

...the LVs were activated before I tried to manage them under virt-manager. Seems like libvirt (or whatever comes here in the play) is deactivating the whole VG if it can't handle a volume (like the mirror one in this case).

Yes, there is a significant fix in F17 related to LVM handling which will affect you:

commit 82c1740ab92682d69ec8f02adb36b13e1902acd1
Author: Osier Yang <jyang>
Date:   Mon Oct 10 20:34:59 2011 +0800

    storage: Do not use comma as seperator for lvs output
    
    * src/storage/storage_backend_logical.c:
    
    If a logical vol is created as striped. (e.g. --stripes 3),
    the "device" field of lvs output will have multiple fileds which are
    seperated by comma. Thus the RE we write in the codes will not
    work well anymore. E.g. (lvs output for a stripped vol, uses "#" as
    seperator here):
    
    test_stripes##fSLSZH-zAS2-yAIb-n4mV-Al9u-HA3V-oo9K1B#\
    /dev/sdc1(10240),/dev/sdd1(0)#42949672960#4194304
    
    The RE we use:
    
        const char *regexes[] = {
            "^\\s*(\\S+),(\\S*),(\\S+),(\\S+)\\((\\S+)\\),(\\S+),([0-9]+),?\\s*$"
        };
    
    Also the RE doesn't match the "devices" field of striped vol properly,
    it contains multiple "device path" and "offset".
    
    This patch mainly does:
        1) Change the seperator into "#"
        2) Change the RE for "devices" field from "(\\S+)\\((\\S+)\\)"
           into "(\\S+)".
        3) Add two new options for lvs command, (segtype, stripes)
        4) Extend the RE to match the value for the two new fields.
        5) Parse the "devices" field seperately in virStorageBackendLogicalMakeVol,
           multiple "extents" info are generated if the vol is striped. The
           number of "extents" is equal to the stripes number of the striped vol.
    
    A incidental fix: (virStorageBackendLogicalMakeVol)
        Free "vol" if it's new created and there is error.
    
    Demo on striped vol with the patch applied:
    
    
    % virsh vol-dumpxml /dev/test_vg/vol_striped2
    <volume>
      <name>vol_striped2</name>
      <key>QuWqmn-kIkZ-IATt-67rc-OWEP-1PHX-Cl2ICs</key>
      <source>
        <device path='/dev/sda5'>
          <extent start='79691776' end='88080384'/>
        </device>
        <device path='/dev/sda6'>
          <extent start='62914560' end='71303168'/>
        </device>
      </source>
      <capacity>8388608</capacity>
      <allocation>8388608</allocation>
      <target>
        <path>/dev/test_vg/vol_striped2</path>
        <permissions>
          <mode>0660</mode>
          <owner>0</owner>
          <group>6</group>
          <label>system_u:object_r:fixed_disk_device_t:s0</label>
        </permissions>
      </target>
    </volume>
    
    RHBZ: https://bugzilla.redhat.com/show_bug.cgi?id=727474

Aha, ok, so it seems it has solved the problem with mirror volumes as well. I think we can close this bug with NEXTRELEASE then if you don't intend to backport the patch for F16... Thanks.

(In reply to comment #4)
> uses "#" as
>     seperator here):
>     
>     test_stripes##fSLSZH-zAS2-yAIb-n4mV-Al9u-HA3V-oo9K1B#\
>     /dev/sdc1(10240),/dev/sdd1(0)#42949672960#4194304

Note that udev permits # in device names:

* Character whitelist: 0-9, A-Z, a-z, #+-.:=@_

Whilst it's unlikely you'll end up with a # within the 'devices' field, it's not impossible (unless you have full control of the system's udev rules and lvm configuration files and avoid it) so it's probably better to pick a character that udev does not permit - an old-fashioned <TAB> is perhaps the obvious choice.
(Comma does work if you put the 'devices' field last and match the correct number of fields.)

Closing NEXTRELEASE as suggested in Comment #5