Running GATHER_SYSTEM_STATS returns MBRC of 1

We have recently migrated a system from one datacenter to another. The database version did not change (11.2.0.4, latest PSU). The OS is still AIX, albeit, it was on 7.1 and is now on 7.2. The SAN is essentially the same (same vendor, same version). The hardware is newer, and supposedly better. So we were really expecting this to be a seamless transition, but instead are fighting some I/O issues. This system is kind of a mixed-load type of system. During the day it does mostly OLTP. Overnight there are some batch processes and in the early morning there are