Hi,

the pvpath command was an addition to the patched LVM1 to control
multipathing. This has vanished
from SLES9 because multipath support is now done in a device-mapper
target. LVM2 does not know
about multipathing anymore. And since a single id for a VG (which was used
to group the paths before)
seems to be on multiple disks it complains. To use multi-pathing there are
now two possible ways:

* Set up multipath regions via EVMS and create volume groups from these.
Which is probably not what
  you really want because that means you have to re(format)/create
everything from scratch.

* Install the multipath-tools package and use it to create the
multi-pathed volumes. You have to exclude
  the real devices (sd[a-z]...) from the lvm2 configuration and include
the created device-mapper devices.
  The trick is to add 'types = [ "device-mapper", 1 ]' to the
configuration file so lvm2 actually considers
  device-mapper volumes. Then you can add the correct filter for the
/dev/xxx.

One note about pav: this does only matter if you use DASD devices and is
only available if Linux runs
within VM. For SCSI attached devices the big deal is whether the volumes
that stand for the different
paths can be accessed without special interaction (some boxes need special
calls and wouldn't be
supported, yet) and if access might be random (some boxes have preferred
pathes and wouldn't
perform very well if the paths are set up to be accessed round-robin).

Regards,
Stefan Bader

SW Linux on zSeries Development & Services
[EMAIL PROTECTED]

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Arty Ecock <[EMAIL PROTECTED]>
Sent by: Linux on 390 Port <[email protected]>
24.06.2005 15:30
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Linux on 390 Port


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Subject
LVM multipathing in SLES9






Hi,

   The "pvpath" command appears to have vanished in SLES9.  We use
"pvpath"
and LVM multipathing for a dozen Linux guests running SLES8.  Using SLES9,
"pvcreate" works fine, but "vgcreate" complains about duplicate "PV"
identifiers (on the alternate path devices).  Although "vgcreate"
indicates
that the volume group was sucessfully created, it isn't.

   I have 8 paths to each FCP LUN on an IBM ESS.  So, /dev/sd[b-h] are the
same devices as /dev/sda.  Works just fine under SLES8.  I am able to
define
the LUN mapping in SLES9 using YaST2 LVM.  I just can't convince
"vgcreate" to
do the right thing.

   Any ideas?

Thanks,
Arty

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