ORACLE11的SGA 受/DEV/SHM大小限制,如何修改/dev/shm大小?

/dev/shm在/etc/fstab中挂载，对应tmpfs，实际使用的是内存的空间。默认情况下，/dev/shm为物理内存大小的一半。因而，调整/dev/shm大小有两种方式：

1. 加大Linux的物理内存
2. 在/etc/fstab中明确指定/dev/shm的挂载sizes大小参数

实际操作步骤

[root@yn-sw1 ~]# df -lh
Filesystem            Size  Used Avail Use% Mounted on
/dev/sda3             450G   32G  396G   8% /
tmpfs                 3.9G  1.8G  2.1G  47% /dev/shm
/dev/sda1             194M   33M  151M  18% /boot
/dev/sdb1             308M   17M  292M   6% /media/OEMDRV



root@yn-sw1 ~]# cat /etc/fstab

#
# /etc/fstab
# Created by anaconda on Sat Sep  2 03:58:07 2017
#
# Accessible filesystems, by reference, are maintained under '/dev/disk'
# See man pages fstab(5), findfs(8), mount(8) and/or blkid(8) for more info
#
UUID=0af842e9-b77a-499b-801e-9ec077d81d21 /                       ext4    defaults        1 1
UUID=fe184602-f1bb-44dd-9e7f-1b9bb6166cba /boot                   ext4    defaults        1 2
UUID=bd746694-847e-48b8-9eb5-fa2d00f9b12b swap                    swap    defaults        0 0
tmpfs                   /dev/shm                tmpfs   defaults        0 0
devpts                  /dev/pts                devpts  gid=5,mode=620  0 0
sysfs                   /sys                    sysfs   defaults        0 0
proc                    /proc                   proc    defaults        0 0
[root@yn-sw1 ~]# cp /etc/fstab /etc/fstab_2070904bk
[root@yn-sw1 ~]# vi /etc/fstab


#
# /etc/fstab
# Created by anaconda on Sat Sep  2 03:58:07 2017
#
# Accessible filesystems, by reference, are maintained under '/dev/disk'
# See man pages fstab(5), findfs(8), mount(8) and/or blkid(8) for more info
#
UUID=0af842e9-b77a-499b-801e-9ec077d81d21 /                       ext4    defaults        1 1
UUID=fe184602-f1bb-44dd-9e7f-1b9bb6166cba /boot                   ext4    defaults        1 2
UUID=bd746694-847e-48b8-9eb5-fa2d00f9b12b swap                    swap    defaults        0 0
tmpfs                   /dev/shm                tmpfs   defaults,size=6144M        0 0
devpts                  /dev/pts                devpts  gid=5,mode=620  0 0
sysfs                   /sys                    sysfs   defaults        0 0
proc                    /proc                   proc    defaults        0 0



重新挂载

[root@yn-sw1 ~]# mount -o remount /dev/shm

[root@yn-sw1 ~]# df -lh
Filesystem            Size  Used Avail Use% Mounted on
/dev/sda3             450G   32G  396G   8% /
tmpfs                 6.0G  1.8G  4.3G  30% /dev/shm
/dev/sda1             194M   33M  151M  18% /boot
/dev/sdb1             308M   17M  292M   6% /media/OEMDRV
/rhel-server-6.4-x86_64-dvd.iso