Problem reusing LVM partitions

[Steve Robson]

Hi all,

   I'm trying to install the OS onto a system, reusing the existing LVM 
partitions thereon.

   I'm using some LVM commands in a %pre section of the config file to 
scan for and create the device nodes and they appear to be executed as 
indicated by their logs.  However, the device node files don't get 
created, hence anaconda complains that it can't locate the partitions I 
requested in the "--onpart" directive and stops.

   Using the console at alt-f2, if I execute verbatim the exact same 
commands, the device nodes are created.  The logs of running the 
commands manually are identical to those when run from %pre.  Can anyone 
offer any help or advice?  Thanks in advance.

-Steve

Herewith, some supporting evidence:
   Error on the console:
     Unable to locate partition mapper/vg00-lroot to use for /.
     Press 'OK' to reboot your system

Relevant sections from my kickstart config file:
   # reusing existing partitions
   part / --onpart=/dev/mapper/vg00-lroot
   part /boot --onpart=/dev/hda1
   part /opt --onpart=/dev/mapper/vg00-lopt
   part /var --onpart=/dev/mapper/vg00-lvar
   part /export/home --onpart=/dev/mapper/vg00-lhome --noformat
   part swap --onpart=/dev/mapper/vg00-lswap

   %pre --interpreter /bin/sh
   # Import LVM data to preserve existing partitions
   /usr/sbin/lvm vgscan --mknodes --ignorelockingfailure --verbose \
     > /tmp/vgscan.log 2>&1
   /usr/sbin/lvm vgchange -a y --ignorelockingfailure --verbose \
     > /tmp/vgchange.log 2>&1

Contents of above named log files:
   vgscan.log:
     Creating directory "/var/lock/lvm"
     Wiping cache of LVM-capable devices
     Wiping internal VG cache
     Finding all volume groups
     Finding volume group "vg00"
     Creating directory "/etc/lvm/archive"
     Archiving volume group "vg00" metadata (seqno 6).
     Creating directory "/etc/lvm/backup"
     Creating volume group backup "/etc/lvm/backup/vg00" (seqno 6).
     Finding all logical volumes
     Reading all physical volumes.  This may take a while...
     Found volume group "vg00" using metadata type lvm2

   vgchange.log
     Finding all volume groups
     Finding volume group "vg00"
     Found volume group "vg00"
     Creating vg00-lroot
     Loading vg00-lroot table
     Resuming vg00-lroot (253:0)
     Found volume group "vg00"
     Creating vg00-lopt
     Loading vg00-lopt table
     Resuming vg00-lopt (253:1)
     Found volume group "vg00"
     Creating vg00-lvar
     Loading vg00-lvar table
     Resuming vg00-lvar (253:2)
     Found volume group "vg00"
     Creating vg00-lswap
     Loading vg00-lswap table
     Resuming vg00-lswap (253:3)
     Found volume group "vg00"
     Creating vg00-lhome
     Loading vg00-lhome table
     Resuming vg00-lhome (253:4)
     Activated logical volumes in volume group "vg00"
   5 logical volume(s) in volume group "vg00" now active

Inspecting /dev/mapper reveals only a character file called "control".
   $ ls -l /dev/mapper
   crw-------  1 root 0  10, 63 Jan  3 11:45 control

   $ ls -l /dev/vg00
   ls: /dev/vg00: No such file or directory

After running the commands manually:
   $ ls -l /dev/mapper
   crw-------  1 root 0  10, 63 Jan  3 11:45 control
   brw-rw----  1 root 6 253,  2 Jan  3 12:09 vg00-lvar
   brw-rw----  1 root 6 253,  3 Jan  3 12:09 vg00-lswap
   brw-rw----  1 root 6 253,  0 Jan  3 12:09 vg00-lroot
   brw-rw----  1 root 6 253,  1 Jan  3 12:09 vg00-lopt
   brw-rw----  1 root 6 253,  4 Jan  3 12:09 vg00-lhome

   $ ls -l /dev/vg00
   lrwxrwxrwx  1 root 0 22 Jan  3 12:09 lhome -> /dev/mapper/vg00-lhome
   lrwxrwxrwx  1 root 0 21 Jan  3 12:09 lopt -> /dev/mapper/vg00-lopt
   lrwxrwxrwx  1 root 0 22 Jan  3 12:09 lroot -> /dev/mapper/vg00-lroot
   lrwxrwxrwx  1 root 0 22 Jan  3 12:09 lswap -> /dev/mapper/vg00-lswap
   lrwxrwxrwx  1 root 0 21 Jan  3 12:09 lvar -> /dev/mapper/vg00-lvar

   I added a "df" and an "lsmod" at the beginning of the %pre section to 
see whether the filesystems aren't mounted when the commands try to run, 
but they are.  Which of course they must be otherwise the commands 
wouldn't be found.  Anyway. here are the df and lsmod results for good 
measure.

   Filesystem            Size  Used Avail Use% Mounted on
   rootfs                6.0M  4.0M  1.8M  70% /
   /dev/root.old         6.0M  4.0M  1.8M  70% /
   bnkick:/images/2007/RHEL4.0_WS_x86
                         121G   87G   28G  76% /mnt/source
   /tmp/loop0            174M  174M     0 100% /mnt/runtime

   Module                  Size  Used by    Not tainted
   cramfs 42421 1 - Live 0xf886f000
   dm_mirror 30637 0 - Live 0xf8939000
   dm_mod 59605 3 dm_snapshot,dm_mirror,dm_zero, Live 0xf8a0e000
   dm_snapshot 17285 0 - Live 0xf89cd000
   dm_zero 2369 0 - Live 0xf88b5000
   ds 17349 44 - Live 0xf8918000
   e100 33733 0 - Live 0xf899c000
   edd 9505 0 - Live 0xf886b000
   ext3 116809 0 - Live 0xf8a90000
   fat 44001 2 msdos,vfat, Live 0xf8896000
   floppy 58481 0 - Live 0xf88fb000
   hermes 7617 2 orinoco_pci,orinoco, Live 0xf8835000
   jbd 71513 1 ext3, Live 0xf89fb000
   lockd 64105 1 nfs, Live 0xf88b7000
   loop 15817 2 - Live 0xf8888000
   mii 5185 1 e100, Live 0xf88a4000
   msdos 10177 0 - Live 0xf8932000
   nfs 232905 1 - Live 0xf8943000
   nfs_acl 3777 1 nfs, Live 0xf883d000
   orinoco 45261 1 orinoco_pci, Live 0xf89a6000
   orinoco_pci 7245 0 - Live 0xf892f000
   parport 37129 1 parport_pc, Live 0xf8a1e000
   parport_pc 24577 0 - Live 0xf8a29000
   pcmcia_core 63481 2 ds,yenta_socket, Live 0xf891e000
   raid0 7617 0 - Live 0xf8936000
   raid1 20033 0 - Live 0xf89b3000
   raid5 25281 0 - Live 0xf89be000
   raid6 101713 0 - Live 0xf89e1000
   scsi_mod 122573 2 sr_mod,sd_mod, Live 0xf897d000
   sd_mod 17217 0 - Live 0xf88a9000
   sr_mod 17381 0 - Live 0xf88af000
   sunrpc 162597 5 nfs,nfs_acl,lockd, Live 0xf88d2000
   uhci_hcd 31065 0 - Live 0xf88c8000
   vfat 14529 0 - Live 0xf888e000
   vga16fb 12201 1 - Live 0xf8829000
   vgastate 8257 1 vga16fb, Live 0xf882d000
   xor 13641 2 raid6,raid5, Live 0xf89b9000
   yenta_socket 18881 0 - Live 0xf890b000