CAA mkcluster fails if repository disk is Clariion/Invista

​Regarding IBM doco - ​​IBM IV53226: CAA MKCLUSTER FAILS IF REPOSITORY DISK IS EMC CLARIION/INVISTA - United States​

​IBM have a local fix (not listed in the article) but have provided us with - ​​ftp://testcase.software.ibm.com/fromibm/aix/IV53226s1a.131211.epkg.Z​

​I'm looking for a more elaborate explanation on this issue from a storage perspective. It claims the mkcluster command on AIX will fail when a hdiskpower is chosen as the repository disk and the underlying SAN is EMC Clariion or Invista. ​

​What is it in particular to the Clariion? Why does this error occur only when using the LUN served by Clariion via PowerPath as a repository disk? I'm not an AIX person so what is the local fix actually fixing?​