说/dev/shm小于SGA_MAX_SIZE 把/dev/shm改大即可

[root@linux5 ~]# df -m
Filesystem           1M-blocks      Used Available Use% Mounted on
/dev/sda2                 9689      7549      1640  83% /
/dev/sda5                16003     11162      4016  74% /db
/dev/sda1                   99        12        82  13% /boot
tmpfs                      502         0       502   0% /dev/shm
[root@linux5 ~]# umount /dev/shm
[root@linux5 ~]# vi /etc/fstab
[root@linux5 ~]# cat /etc/fstab
LABEL=/                 /                       ext3    defaults        1 1
LABEL=/db               /db                     ext3    defaults        1 2
LABEL=/boot             /boot                   ext3    defaults        1 2
tmpfs                   /dev/shm                tmpfs   defaults,size=1024m        0 0
devpts                  /dev/pts                devpts  gid=5,mode=620  0 0
sysfs                   /sys                    sysfs   defaults        0 0
proc                    /proc                   proc    defaults        0 0
LABEL=SWAP-sda3         swap                    swap    defaults        0 0
[root@linux5 ~]# mount /dev/shm

再次启动数据库就OK了

SQL> startup
ORACLE instance started.

Total System Global Area  626327552 bytes
Fixed Size                  2215944 bytes
Variable Size             599789560 bytes
Database Buffers           20971520 bytes
Redo Buffers                3350528 bytes
Database mounted.
Database opened.
SQL>