RMAN-04014: startup failed: ORA-00845: MEMORY_TARGET not supported on this system

connected to auxiliary database (not started)
RMAN-00571: ===========================================================
RMAN-00569: =============== ERROR MESSAGE STACK FOLLOWS ===============
RMAN-00571: ===========================================================
RMAN-03002: failure of Duplicate Db command at 06/23/2014 16:19:21
RMAN-05501: aborting duplication of target database
RMAN-03015: error occurred in stored script Memory Script
RMAN-04014: startup failed: ORA-00845: MEMORY_TARGET not supported on this system

Increase size of tmpfs

[root@ol6-112-rac2 ~]# cat /etc/fstab|grep tmpfs
tmpfs                   /dev/shm                tmpfs   defaults,size=4G        0 0
[root@ol6-112-rac2 ~]# mount -o remount tmpfs
[root@ol6-112-rac2 ~]# mount
/dev/mapper/vg_ol6112rac1-lv_root on / type ext4 (rw)
proc on /proc type proc (rw)
sysfs on /sys type sysfs (rw)
devpts on /dev/pts type devpts (rw,gid=5,mode=620)
tmpfs on /dev/shm type tmpfs (rw,size=4G)