PowerPath: "pprootdev on" command fails because hd5 logical volume is too small

pprootdev on command fails with the following errors:

dd: 0511-053 The write failed.
: There is a request to a device or address that does not exist.
35509+1 records in.
554+1 records out. 
0301-161 bosboot: dd failed to copy bootimage.
 
0301-165 bosboot: WARNING! bosboot failed - do not attempt to boot device.
pprootdev: bosboot has failed.  The configuration change has not been saved to the boot device.

The PowerPath script pprootdev on calls the bosboot command to create a new boot image and store it into the boot logical volume specified. With PowerPath enabled, the boot image can have a size >32 Mb. The logical volume has a size of one Physical Partition (PP), but if the PPSIZE of rootvg is 32 Mb then the volume size will be 32 Mb which is too small to store the boot image.
The size of a PP depends on the size of the disk itself. The larger the disk is, the larger the size of a PP.

Three different methods exist to increase the size of a logical volume. Volume hd5 is assumed in the examples below:

Method 1 - adding a Physical Partition (PP) to hd5
The partitions hd5 is on must be contiguous, and in the first 4 GB of the hard disk. If you want to know if there are any free partitions available next to hd5, run the following command:

# lspv -M hdisk0    (hdisk0 = rootvg disk)
hdisk0:1        hd5:1
hdisk0:2-15
hdisk0:16       fslv00:1
hdisk0:17       fslv00:2

1. Use extendlv command to add a second partition to hd5. For this example, we would create a file called "Map" for example, and in the file we would have only one line with hdisk0:2. Then we would run extendlv -m Map hd5 1. This would extend hd5 by one PP starting at hdisk0:2. This would guarantee that the extend is contiguous.

2. Run pprootdev on command (if you run into the issue after running pprootdev on, this second attempt to run pprootdev on will fail because the previous one partially succeeded. This means that you will probably have to create a new copy of your boot disk to repeat the whole procedure again… and extend hd5 LV BEFORE running pprootdev on).

Method 2 - changing hd5 layout in rootvg with alt_disk_copy utility

1. Run mkszfile command. This command creates a file /image.data which is the layout of rootvg.

2. Edit the image.data file and adjust LPs and LV_MIN_LPS for hd5 (we need one more PP. Therefore, if LPs and LV_MIB_LPS are set to 1, change these values to 2)

   Example:

   lv_data:
           VOLUME_GROUP= rootvg                                VOLUME_GROUP= rootvg
           LV_SOURCE_DISK_LIST= hdisk4                         LV_SOURCE_DISK_LIST= hdisk4
           LV_IDENTIFIER= 00f98edf00004c00000001860d2daee6.1   LV_IDENTIFIER= 00f98edf00004c00000001860d2daee6.1
           LOGICAL_VOLUME= hd5                                 LOGICAL_VOLUME= hd5
           VG_STAT= active/complete                            VG_STAT= active/complete
           TYPE= boot                                          TYPE= boot
           MAX_LPS= 512                                        MAX_LPS= 512
           COPIES= 1                                           COPIES= 1
           LPs= 1                                              LPs= 2
           STALE_PPs= 0                                        STALE_PPs= 0
           INTER_POLICY= minimum                               INTER_POLICY= minimum
           INTRA_POLICY= edge                                  INTRA_POLICY= edge
           MOUNT_POINT=                                        MOUNT_POINT=
           MIRROR_WRITE_CONSISTENCY= on/ACTIVE                 MIRROR_WRITE_CONSISTENCY= on/ACTIVE
           LV_SEPARATE_PV= yes                                 LV_SEPARATE_PV= yes
           PERMISSION= read/write                      ==>     PERMISSION= read/write
           LV_STATE= closed/syncd                              LV_STATE= closed/syncd
           WRITE_VERIFY= off                                   WRITE_VERIFY= off
           PP_SIZE= 128                                        PP_SIZE= 128
           SCHED_POLICY= parallel                              SCHED_POLICY= parallel
           PP= 1                                               PP= 1
           BB_POLICY= non-relocatable                          BB_POLICY= non-relocatable
           RELOCATABLE= no                                     RELOCATABLE= no
           UPPER_BOUND= 32                                     UPPER_BOUND= 32
           LABEL= primary_bootlv                               LABEL= primary_bootlv
           MAPFILE=                                            MAPFILE=
           LV_MIN_LPS= 1                                       LV_MIN_LPS= 2
           STRIPE_WIDTH=                                       STRIPE_WIDTH=
           STRIPE_SIZE=                                        STRIPE_SIZE=
           SERIALIZE_IO= no                                    SERIALIZE_IO= no
           FS_TAG=                                             FS_TAG=
           DEV_SUBTYP=                                         DEV_SUBTYP=

3. Clone rootvg using the command: alt_disk_copy -i /image.data -d hdiskY (hdiskY is the target disk)

4. Reboot the server to activate the cloned disk (with new PP size)

5. Run pprootdev on command

Method 3 - re-creating hd5
As previously mentioned, the partitions hd5 is on must be contiguous, and in the first 4 GB of the hard disk. If you want to know if there are any free partitions available next to hd5, run the following command:

# lspv -M hdisk0    (hdisk0 = rootvg disk)
hdisk0:1        hd5:1
hdisk0:2        fslv00:1
hdisk0:3        fslv00:2

1. In the above example, there is no free PP after the first one used by hd5. Using an extendlv will not work since the extra PP will not be contiguous. Since hd5 only contains the boot record and this contents can be generated with a bosboot command, we can completely re-create hd5.

   # rmlv -f hd5 (hdisk0 = rootvg disk)
   # mklv -y hd5 -t boot -u2 rootvg 2 hdisk0

2. We can then check with an lspv -M hdiskXX that the newly created hd5 now has two consecutive PP.

   # lspv -M hdisk0    (hdisk0 = rootvg disk)
   hdisk0:1
   hdisk0:2        fslv00:1
   hdisk0:3        fslv00:2
   ....
   hdisk0:13       hd5:1
   hdisk0:14       hd5:2

The pprootdev on command should now succeed, assuming that the hd5 LV was created within the first 4 GB (this is what the documentation says, but this depends on the AIX release and with AIX 7.2 TL5, the limit is higher). Therefore, and before running a pprootdev on, run a bosboot! If the bosboot cannot find hd5, it means that it is too far away from the beginning of the disk and pprootdev on will fail as well: The change must be undone (rmlv -f hd5; mklv -y hd5 -t boot -u1 rootvg 1 hdiskX) and method 2 must be used.