MTSAPHANA:~ # su hd1adm
su: /bin/sh: Permission denied
my first idea would have been that hd1adm does not have sufficient rights to the cwd, but a quick verification on SLES11SP1 and SP3 shows that su using /bin/sh works fine even without r/x rights to the current directory.
Is /bin/sh actually executable? Does hd1adm have all required rights to /bin/sh?