centos 7.x 的一些系统层面设置

安装数据库经常做一些os的设置，简单总结一下，随时补充

rc.local

# vi /etc/rc.local

############################################
#disable transparent hugepage
############################################
if test -f /sys/kernel/mm/transparent_hugepage/enabled; then
   echo never > /sys/kernel/mm/transparent_hugepage/enabled
fi
if test -f /sys/kernel/mm/transparent_hugepage/defrag; then
   echo never > /sys/kernel/mm/transparent_hugepage/defrag
fi

############################################
#set read block size
############################################
blockdev --setra 16384 /dev/sda

############################################
#set io scheduler to deadline for every disk
############################################
echo deadline > /sys/block/sda/queue/scheduler

############################################
#set write type 
# 0:write through
# 1:write back
# hdparm -I /dev/sda |grep "Write cache"
# hdparm -W 0 /dev/sda
# hdparm -W 1 /dev/sda
############################################
hdparm -W 0 /dev/sda 

grant exec

# chmod u+x /etc/rc.d/rc.local

sysctl.conf

# vi /etc/sysctl.conf

kernel.shmall = 18446744073692774399    
kernel.shmmax = 18446744073692774399    
kernel.shmmni = 819200 

kernel.sem = 4096 2147483647 2147483646 512000 

net.core.rmem_default = 262144    
net.core.rmem_max = 4194304    
net.core.wmem_default = 262144    
net.core.wmem_max = 4194304 

net.ipv4.tcp_rmem=8192 87380 16777216    
net.ipv4.tcp_wmem=8192 65536 16777216  

net.ipv4.tcp_keepalive_intvl=20    
net.ipv4.tcp_keepalive_probes=3    
net.ipv4.tcp_keepalive_time=60 

net.ipv4.tcp_mem=8388608 12582912 16777216  
net.ipv4.ip_local_port_range=10000 65535  

vm.dirty_background_bytes = xxxx000000    
vm.dirty_expire_centisecs = 6000    
vm.dirty_ratio = 80    
vm.dirty_writeback_centisecs = 50

vm.overcommit_memory = 2
vm.overcommit_ratio = 90
vm.swappiness = 1

vm.nr_hugepages = xxxx

fs.nr_open=20480000
fs.file-max=7672460
fs.aio-max-nr=1048576

生效

# sysctl -p
# sysctl -a

resource limit

# vi /etc/security/limits.conf

root soft nofile  655360 # The maximum number of open file descriptors
root hard nofile  655360

root soft nproc   655360 # The maximum number of processes available to a single user
root hard nproc   655360

* soft memlock unlimited # The maximum size that may be locked into memory
* hard memlock unlimited

* soft core    unlimited # The maximum size of core files created
* hard core    unlimited

* soft stack   unlimited  
* hard stack   unlimited 

disable selinux

# vi /etc/selinux/config
SELINUX=DISABLED

disable firewalld

# systemctl stop firewalld.service
# systemctl disable firewalld.service

disable ipv6

# vi /etc/default/grub
ipv6.disable=1

disable numa

# vi /etc/default/grub
numa=off 

disable transparent hugepage

# vi /etc/default/grub
transparent_hugepage=never 

set all disk ioscheduler

# vi /etc/default/grub
elevator=deadline

new grub

# grub2-mkconfig -o /boot/grub2/grub.cfg