How do you update your server OS? Minor update is not a problem because you only need to do is ‘yum update’. Kernel is included in this update so you don’t worry about it, right? But how about major update such as CentOS5 to CentOS6? Maybe most of OS suggest clean install. This is because major update. Of course, it is true. Imagine that some former mechanizm is not erased and still working. And whathappen if new one is completely different and working at the same time?
Engineer could prepare about it, but they don’t want to do that. If they have such time to do it, they want to spend it for another developments. This is happen only once and there is another way, it is clean install. so did I.
Anyway, before you update your OS, you have to think about what you should make backups. For me, like follows.
- environment /etc, other setting
- personal data /home
- web site /var/www
- mysql data, this is part of web site
First 3 contents does not have any issue, you just use ‘tar zcvf ***.tar.gz /***/***’.
So how do you create your database backup? It depends on your situation. When you need to create it with database running, it is not easy. MySQL has a command ‘mysqldump’, not only MySQL but other database system has also their own command to make backup. Actually it is not so hard. But if you could stop it, it is really easy. You stop MySQL then make a backup ‘tar zcvf ***.tar.gz /var/lib/mysql’. This is it. Done.
And don’t forget ‘other setting’. Some programs are used to install /usr/local folder such as squid. You had better keep these setting.