Warning added to chdev if byte 0-3 has a known value.

Request a fix / warning added to chdev if byte 0-3 has a known value.

The "chdev ... pv=yes" changes byte 0-3 along with adding a PVID.

Command "chdev -l hdiskX -a pv=y in addition to placing a PVID on the disk it changes byte 0-3 to C9C2D4C1 (IBMA).
"C9C2D4C1" is the AIX disk identifier EBCDIC (hex) for "IBMA".
When the disk used as a boot disk by an IBM i VIO client this change to byte 0-3 will cause the IBM i boot to fail.
If "chdev ... pv=yes" had a check for known valid values for Disk Identifier and displayed a warning an accidental corruption of IBM i boot disk can be avoided.

This issue has been encountered at several customer locations.

A check added to chdev pv=y for a valid disk identifier and warn the user so they do not corrupt an IBM i boot disk would save support calls, and some sites from trying to debug boot (IPL) failures.

Technote N1012691 provides the recovery procedure, however, the SRCB2004158 is generic enough where this document is not always quickly found.

i5 Client Partition with VIOS (Virtual I/O Server) Host Partition Fails to Boot with SRCB2004158 When PVID is Set in VIOS
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http://www-01.ibm.com/support/docview.wss?uid=nas8N1012691

Output of the disk after putting a PVID on the disk.

# lquerypv -h /dev/hdisk0
00000000 C9C2D4C1 00000000 00000000 00000000 |................|
00000010 00000000 00000000 00000000 00000000 |................|
00000020 00000000 00000000 00000000 00000000 |................|
00000030 00000000 00000000 00000000 00000000 |................|
00000040 00000000 00000000 00000000 00000000 |................|
00000050 00000000 00000000 00000000 00000000 |................|
00000060 00000000 00000000 00000000 00000000 |................|
00000070 00000000 00000000 00000000 00000000 |................|
00000080 00ABCABC ABCABCAB 00000000 00000000 |...7._..........|