Create a new image.data file by running the following command:

# cd /
# mkszfile

Edit the image.data file to break the mirror, by running the following command:

# vi /image.data

What you are looking for are the "lv_data" stanzas. There will be one for every logical volume associated with rootvg.

The following is an example of an lv_data stanza from an image.data file of a mirrored rootvg. The lines that need changing are marked bold:

lv_data:
VOLUME_GROUP= rootvg
LV_SOURCE_DISK_LIST= hdisk0 hdisk1
LV_IDENTIFIER= 00cead4a00004c0000000117b1e92c90.2
LOGICAL_VOLUME= hd6
VG_STAT= active/complete
TYPE= paging
MAX_LPS= 512
COPIES= 2
LPs= 124
STALE_PPs= 0
INTER_POLICY= minimum
INTRA_POLICY= middle
MOUNT_POINT=
MIRROR_WRITE_CONSISTENCY= off
LV_SEPARATE_PV= yes
PERMISSION= read/write
LV_STATE= opened/syncd
WRITE_VERIFY= off
PP_SIZE= 128
SCHED_POLICY= parallel
PP= 248
BB_POLICY= non-relocatable
RELOCATABLE= yes
UPPER_BOUND= 32
LABEL=
MAPFILE= /tmp/vgdata/rootvg/hd6.map
LV_MIN_LPS= 124
STRIPE_WIDTH=
STRIPE_SIZE=
SERIALIZE_IO= no
FS_TAG=
DEV_SUBTYP=

Note: There are two disks in the 'LV_SOURCE_DISK_LIST', THE 'COPIES' value reflects two copies, and the 'PP' value is double that of the 'LPs' value.

The following is an example of the same lv_data stanza after manually breaking the mirror. The lines that have been changed are marked bold. Edit each 'lv_data' stanza in the image.data file as shown below to break the mirrors.

lv_data:
VOLUME_GROUP= rootvg
LV_SOURCE_DISK_LIST= hdisk0
LV_IDENTIFIER= 00cead4a00004c0000000117b1e92c90.2
LOGICAL_VOLUME= hd6
VG_STAT= active/complete
TYPE= paging
MAX_LPS= 512
COPIES= 1
LPs= 124
STALE_PPs= 0
INTER_POLICY= minimum
INTRA_POLICY= middle
MOUNT_POINT=
MIRROR_WRITE_CONSISTENCY= off
LV_SEPARATE_PV= yes
PERMISSION= read/write
LV_STATE= opened/syncd
WRITE_VERIFY= off
PP_SIZE= 128
SCHED_POLICY= parallel
PP= 124
BB_POLICY= non-relocatable
RELOCATABLE= yes
UPPER_BOUND= 32
LABEL=
MAPFILE= /tmp/vgdata/rootvg/hd6.map
LV_MIN_LPS= 124
STRIPE_WIDTH=
STRIPE_SIZE=
SERIALIZE_IO= no
FS_TAG=
DEV_SUBTYP=

Note: The 'LV_SOURCE_DISK_LIST' has been reduced to one disk, the 'COPIES' value has been changed to reflect one copy, and the 'PP' value has been changed so that it is equal to the 'LPs' value.

Save the edited image.data file. At this point you can use the edited image.data file to do one of the following: You can now use your newly edited image.data file to create a new mksysb to file, tape, or DVD.

E.g.: To file or tape: place the edited image.data file in the / (root) directory and rerun your mksysb command without using the "-i" flag. If running the backup through SMIT, make sure you set the option "Generate new /image.data file?" to 'no' (By default it is set to 'yes').

To DVD: Use the -i flag and specify the [/location] of the edited image.data file. If running through SMIT specify the edited image.data file location in the "User supplied image.data file" field.

Within NIM you would create an 'image_data' resource for use with NIM to restore a mksysb without preserving mirrors.

Note: If you don't want to edit the image.data file manually, here's a script that you can use to have it updated to a single disk for you, assuming your image_data file is called /image.data:

cat /image.data | while read LINE ; do
  if [ "${LINE}" = "COPIES= 2" ] ; then
    COPIESFLAG=1
    echo "COPIES= 1"
  else
    if [ ${COPIESFLAG} -eq 1 ] ; then
      PP=`echo ${LINE} | awk '{print $1}'`
      if [ "${PP}" = "PP=" ] ; then
        PPNUM=`echo ${LINE} | awk '{print $2}'`
        ((PPNUMNEW=$PPNUM/2))
        echo "PP= ${PPNUMNEW}"
        COPIESFLAG=0
      else
        echo "${LINE}"
      fi
    else
      echo "${LINE}"
    fi
  fi
done > /image.data.1disk

If you found this useful, here's more on the same topic(s) in our blog:

• Creating an image_data resource without preserving mirrors for use with NIM
• Tivoli Storage Manager introduction
• Translate hardware address to physical location
• Truss
• Configuring NTP on CentOS 6