CentOS 7.0 experiences different from previous versions

CentOS 7.0 experiences different from previous versions

[Editor's note] as a system administrator of CentOS 6, I feel uncomfortable when I first experience CentOS 7...

This afternoon, I had nothing to do. I installed a CentOS 7 on a machine and found that it was very different from the previous version. I don't know if rhel7 is the same. After all, CentOS is RedHat now.

Installation

First, during installation, all the previously rhel-series (including centos and Fedora) packages can be selected, but now only one option can be selected, with repeated sub-options; when the selected partition is installed, the recommended partition for centos7 is xfs, instead of the previous ext (2, 3, 4) series. The installation is roughly the same.

Official CentOS 7 release and download

64-bit CentOS 6.5 Installation Method

64-bit CentOS 6.4 dual-system installation in Win7

Precautions for installing CentOS and Windows systems

Install Windows 8 and CentOS on UEFI + GPT

Windows 8.1 and CentOS6.5 dual-system installation

Basic Optimization after CentOS 5.6 Linux is installed

Initial start

After the host is installed, the system interface is changed when the system is started. At first glance, it seems that there are two kernels. One is the rescue option, and after pressing e, all grub will be found. the conf information is complete, so it is hard to find the kernel to start, write a 1 (to enter the single user mode), and then enter the rescue mode.

Character Interface

After entering the system, it is a graphical interface. To enter the character interface, find the/etc/inittab and find that it is almost an empty file. If the file prompts you to change the runlevel, you can set/lib/systemd/system/runlevel *. target is soft connected to/etc/systemd/system/default.tar get (of course, You can overwrite it). After trying it, you can change it to runlevel3 on the Character interface.

Configure the network and Host Name

Then, if you want to configure the network, go to/etc/sysconfig/network-script/and check that the NIC has changed its name to enp1s5. This is interesting. After configuring the network, change the host name, change the name to/etc/sysconfig/network and find that the file is empty. Modify the file according to the previous version 6. It will not work after restart. man has a hostname, in the case of 7, you need to change the name to/etc/hostname.

Local yum source and Mount

Next, you want to configure a local yum source, and then you need to mount the CD, manually mount it, And then directly echo "mount ...... "To rc. local. After all, the script is started and executed. After the restart, the script is not mounted. Go to rc. in local, I saw that chmod + x rc should be manually executed in 7. local: Yes. You need to manually add the execution permission. Do you have to manually add the execution permission in the systems I installed before 6 !!!! Of course, after the permission is added, the mount command of rc. local is started after the instance is started.

LVM and xfs

Later, I wanted to dress up with an lvm for fun, so I tried partitioning and formatting (specially formatted as xfs), pv, vg, and lv step by step. It was okay, so I wanted to zoom in and out, when resize2fs is executed, how does one always report a superblock error? What is the problem? man resize2fs then finds that this command only supports ext file systems, then how is the installation of the system lvm? I have not solved this problem yet. There should be a solution.

Dhcp and services

Next, I want to dress a dhcp game. I was surprised to find that after packaging all dhcp, I couldn't start service dhcpd, and then found/etc/init. d/does not have a dhcp similar thing. After all, there were dhcpd, dhcpd6, and dhcrelay before 6, and then we found that/sbin/dhcpd had a STARTUP file. Isn't it, if you want to enable services in the future, do you have to manually compile them? Wrong, it is in/usr/lib/systemd/system/dhcpd. service, there are still many modifications, and then add permissions to execute service restart/stop ...... Yes, but it points to the systemctl restart/start/stop service. service

Iptables

I also found that iptables is not a service in/etc/init. d/this time, but under/sbin;

Then, there will be no more. Maybe, it is true or not. discover new things and update them on this log. It is true or not.

By the way, I also found that/etc/sysctl. conf is empty, and all route forwarding requests to/proc/sys/net are required.