If CPLEXD fails on AIX with an error like

Symbol resolution failed for /usr/lib/libc.a[posix_aio_64.o] because:
      Symbol _posix_kaio_rdwr64 (number 2) is not exported from dependent module /unix.
      Symbol _posix_listio64 (number 3) is not exported from dependent module /unix.

then the AIX system need to be setup such that asynchronous I/O is configured and enabled. To do so, follow the instructions here.