Sysback restore from MPIO SAN Disks

Answer

Lately, MPIO is becoming more and more popular, due to two big advantages : it provides – redundancy, and depending on the configuration, increased I/O throughput. A disk being presented by multiple paths can improve your system's performance but sometimes problems come up when trying to restore a backup to a disk with multiple paths. Since according to the PCM (Path Control Module) used each path to the disk can have the same PVID. The 'bosboot' and 'varyonvg' commands can sometimes fail to run successfully, which can cause the restore to fail. A fix has been implemented in the mksysb backup code, but it was not present in the Sysback code.
As the defect was found recently, an APAR has been opened to address the problem and the official fix should be released in the next version of Sysback.
There is a defect with Sysback (versions 6.1.3.9 and lower) on multipath disks which produce the errors below:

Making rootvg volume group on disks: hdiskX
0516-1775 /usr/sbin/varyonvg: Physical volumes hdiskX and hdiskY have identical PVIDs (00c5b1f77b6d92b4).
0516-862 mkvg: Unable to create volume group.
Error creating rootvg - using defaults...
0516-1775 /usr/sbin/varyonvg: Physical volumes hdiskX and hdiskY have identical PVIDs (00c5b1f77b6d92b4).
0516-862 mkvg: Unable to create volume group.

This defect was first seen in the mksysb command in AIX (APAR IV30772: MKSYSB RESTORE FROM MPIO SAN DISKS MAY FAIL WITH DUPLICATE PVIDS).

This defect will be fixed with Sysback APAR: IT20378. The official fix should be released with the next version of Sysback, and currently it is not available for download. Until the next official release is out, use the below workaround.

In order to provide the workaround, APAR IV30772 must be installed on the system and/or the NIM SPOT (depends on the type of boot). Systems running the 6100-07 Technology Level with the bos.rte.lvm fileset below the 6.1.7.19 level or 7100-01 Technology Level with the bos.rte.lvm fileset below the 7.1.1.19 level are affected by the APAR mentioned above, and You need to update Your AIX level to a higher one.

This can be verified in two different ways:
1. Use the instfix command:
# instfix –ik IV30772

2. Check the varyonvg command:
# strings /usr/sbin/varyonvg | grep –i skip
or
# strings /etc/varyonvg | grep –i skip

The expected output should be similar to this:

SKIP_DUPPVID_CHECK
get_config_pvnames: SKIP_DUPPVID_CHECK environment variable set

Once you have confirmed that the AIX fix is in place, you can follow the steps below to apply it for Sysback booting.

Whether you are doing a CD/DVD, tape or classic network boot, the fix is the same. You need to edit the sysinst.lib file which contains commonly used functions and variables which sysback calls on.

# cd /usr/lpp/sysback/inst

# cp sysinst.lib sysinst.lib.MMDDYYYY

f.e.# cp sysinst.lib sysinst.lib.04242017

# vi sysinst.lib

Next, modify this line:

###########################
# Main
###########################
[ -z "$NORMAL" ] && trap 'startshell' 2

# Set LVFIELDS variable. Determines the fields in the VG line of the VGINFO file

-----------------
TO BE THIS:
-----------------

###########################
# Main
###########################
[ -z "$NORMAL" ] && trap 'startshell' 2

export SKIP_DUPPVID_CHECK=1 #Add this line

# Set LVFIELDS variable. Determines the fields in the VG line of the VGINFO file


Save and exit the file and remake the boot image
- if doing a classic network boot:
# mksbnetboot –B ‘all’

- if doing a CD/DVD/tape boot, recreate the backup to the respective media.


If you are doing a NIM resource boot, you need to edit the same file, but this time in the SPOT that you are using to boot:

# lsnim –l <spot> | grep location

It should return an output similar to:

location = /export/spot/71TL4_base_spot/71TL4_base_spot/usr

Next, edit the sysinst.lib in the location of the SPOT:
# cd /export/spot/71TL4_base_spot/71TL4_base_spot/usr/lpp/sysback/inst
# vi sysinst.lib

Next, modify this line:

###########################
# Main
###########################
[ -z "$NORMAL" ] && trap 'startshell' 2

# Set LVFIELDS variable. Determines the fields in the VG line of the VGINFO file

-----------------
TO BE THIS:
-----------------

###########################
# Main
###########################
[ -z "$NORMAL" ] && trap 'startshell' 2

export SKIP_DUPPVID_CHECK=1 #Add this line

# Set LVFIELDS variable. Determines the fields in the VG line of the VGINFO file


Save and exit the file and remake the boot image
# mksbnetboot –B ‘all’

Thank you for the time to read through this guide. I hope you found the information both useful and helpful. If you feel there are any mistakes or inconsistencies, please email me at ted.todorov@bg.ibm.com. If there are any technical questions regarding this document, please follow support procedures and open a PMR by calling 1-800-426-7378, and select the option for software support.