Some versions of glibc released as updates of RHEL6 on x86_64 and i686 change the behavior of the memcpy routine: calling memcpy with overlapping range produces unexpected behavior. While these changes do not violate any standards, they constitute a departure from previous behavior, and in doing so expose significant problems in GPFS code, leading to a variety of symptoms.
The memcpy behavior change has turned out to be problematic in some other aspects, and RedHat has since released an updated version of glibc that restores the old memcpy behavior. See http://rhn.redhat.com/errata/RHSA-2012-0393.html for details.
The list of affected glibc versions includes (but is not limited to):
Version glibc-2.12-1.47.el6_2.9 and later do not have the problem. Be sure to not upgrade any nodes running any version of GPFS to a problematic version of glibc, and install a fixed version if such an upgrade has already occurred.
GPFS Development Team