Centos7 腾讯云禁用kdump节省内存

由于Centos系统为 kdump 服务预留了一部分内存导致服务器内存显示不足实际购买 4G

[root@VM_0_9_centos ~]# free -m
total used free shared buff/cache avAIlable
Mem: 3789 898 102 35 2788 2540
Swap: 0 0 0
停止kdump服务

停止并禁止自启动

[root@VM_0_9_centos ~]# systemctl stop kdump.service
[root@VM_0_9_centos ~]# systemctl disable kdump.service
修改grub文件

将crashkernel=auto修改为crashkernel=0

[root@VM_0_9_centos ~]# vim /etc/default/grub

GRUB_TIMEOUT=5
GRUB_DISTRIBUTOR=“$(sed s, release .*$,,g /etc/system-release)”
GRUB_DEFAULT=saved
GRUB_DISABLE_SUBMENU=true
GRUB_TERMINAL=“serial console”
GRUB_TERMINAL_OUTPUT=“serial console”
GRUB_CMDLINE_LINUX=“crashkernel=0 console=ttyS0 console=tty0 panic=5 net.ifnames=0 biosdevname=0”
GRUB_DISABLE_RECOVERY=“true”
GRUB_SERIAL_COMMAND=“serial –speed=9600 –unit=0 –word=8 –parity=no –stop=1”
生成配置并重启

重启前注意无其他正在进行的工作，以免造成数据丢失

[root@VM_0_9_centos ~]# grub2-mkconfig -o /boot/grub2/grub.cfg
[root@VM_0_9_centos ~]# reboot
验证

减少了161MB内存

[root@Nginx-server logs]# free -mtotal used free shared buff/cache availableMem: 3950 898 2502 32 550 2792
Swap: 0 0 0
其他

查看底层硬件信息，可以看到这台轻量云 2G 内存的服务器是分配足了 2048M 内存的。

[root@VM_0_9_centos ~]# dmidecode |egrep “Maximum|Size”
Runtime Size: 96 kB
ROM Size: 64kB
Maximum Capacity:4 GB
Size: 4096 MB
Range Size: 3584 MB
Range Size: 512MB
Range Size:3584 MB
Range Size: 512 MB

Reserving

[root@VM_0_9_centos ~]# dmesg | grep -i memory
[ 0.000000] Base memory trampoline at [ffff9f7000099000]99000 size 24576
[ 0.000000] Early memory node ranges
[ 0.000000] PM: Registered nosave memory: [mem 0x0009f000-0x0009ffff]
[ 0.000000] PM: Registered nosave memory: [mem0x000a0000-0x000effff]
[ 0.000000] PM: Registered nosave memory: [mem 0x000f0000-0x000fffff]
[ 0.000000] PM: Registered nosave memory: [mem 0xdfffe000-0xdfffffff]
[ 0.000000] PM: Registered nosave memory: [mem 0xe0000000-0xfeffbfff]
[ 0.000000] PM: Registered nosave memory: [mem0xfeffc000-0xfeffffff]
[ 0.000000] PM: Registered nosave memory: [mem0xff000000-0xfffbffff]
[ 0.000000] PM: Registered nosave memory: [mem 0xfffc0000-0xffffffff]
[ 0.000000] Memory: 4024148k/4718592k available (7664k kernel code, 524688k absent, 169756k reserved,6055k data, 1876k init)
[ 0.000000] please try cgroup_disable=memory option if you dont want memory cgroups
[ 0.024204] Initializing cgroup subsys memory
[ 0.556576] Freeing initrd memory:18236k freed
[ 0.699529] Non-volatile memory driver v1.3
[ 0.702670] crash memory driver: version1.1
[ 0.840195] Freeing unused kernel memory: 1876k freed
[ 0.845600] Freeing unused kernel memory:516k freed
[ 0.848671] Freeing unused kernel memory: 600k freed
[1.579629] [TTM] Zone kernel: Available graphics memory: 2022702 kiB