Mongodb安装过程中的问题

1、** WARNING: /sys/kernel/mm/transparent_hugepage/enabled is ‘always’.
 **        We suggest setting it to ‘never’

** WARNING: /sys/kernel/mm/transparent_hugepage/defrag is ‘always’.
 **        We suggest setting it to ‘never’

临时解决方案：
echo "never" > /sys/kernel/mm/transparent_hugepage/enabled
echo "never" > /sys/kernel/mm/transparent_hugepage/defrag
systemctl restart mongod

永久解决方案：(此中方案仅能使/sys/kernel/mm/transparent_hugepage/enabled生效)
# vim /etc/default/grub
GRUB_CMDLINE_LINUX="crashkernel=auto 
rd.lvm.lv=centos/root rd.lvm.lv=centos/swap rhgb quiet transparent_hugepage=never"

# grub2-mkconfig -o /boot/grub2/grub.cfg 
Generating grub configuration file ...
Found linux image: /boot/vmlinuz-3.10.0-327.el7.x86_64
Found initrd image: /boot/initramfs-3.10.0-327.el7.x86_64.img
Found linux image: /boot/vmlinuz-0-rescue-109209786e3a48efae39e12ae1c8e74c
Found initrd image: /boot/initramfs-0-rescue-109209786e3a48efae39e12ae1c8e74c.img
done

#reboot 重启

推荐使用方案 - 永久解决:
官方教程：https://docs.mongodb.com/manual/tutorial/transparent-huge-pages/
参考 Init Script 部分

2、** WARNING: soft rlimits too low. rlimits set to 4096 processes, 65536 files. Number of processes should be at least 32768 : 0.5 times number of files.

参考官方的解决方法：https://docs.mongodb.com/manual/reference/ulimit/

# vim /etc/security/limits.d/20-nproc.conf
*       soft    nofile  524288
*       hard    nofile  524288

*       soft    nproc  524288
*       hard    nproc  524288

*       soft   fsize  unlimited
*       hard   fsize  unlimited

*       soft   cpu  unlimited
*       hard   cpu  unlimited

*       soft   as  unlimited
*       hard   as  unlimited

3、mongod关机后，无法启动

#删除lock文件，创建pid的运行目录
rm -f /data/mongod/mongod.lock
mkdir -p /run/mongod/chown mongod:mongod /run/mongod

 4、mongod启动
about to fork child process, waiting until server is ready for connections.
forked process: 4113
ERROR: child process failed, exited with error number 14

查看日志文件发现：
[initandlisten] Failed to unlink socket file /tmp/mongodb-27017.sock errno:1 
Operation not permitted

rm  -f /tmp/mongodb-27017.sock