My two cents on "the new Linux" -> RedHat EL7 / CentOS 7.
7 is a huge step forward over previous releases and I was ready for big changes.
Let's start to summarize only few new things.
Kernel 3.1x
FirewallD
SystemD
mariaDB
wait… someone saied in place upgrade.
There are dozens of other changes but this ones cought my attention.
I use Linux since years and every time I need to switch to a major version I know that I need to spend
a lot of time to reconfigure all the stuff and learn what's new to configure them on their best.
In place upgrade is a "miracle feature" that doesn't exist and that cannot work on a real life server.
I have spent 7 days to switch from CentOS 6.5 to CentOS 7, no automatic tool can do this automatically.
My server is quite simple, I have:
Apache (PHP), some vhost, ipv6
Tomcat (Java)
iptables
Various init.d scripts
various cron
fail2ban
custom logrotate
Postfix
Sieve filtering
Amavisd
Dovecot
Roundcubemail
A multiplexer to "workaround" hotel/company firewalls while offering service from 443
snmpd
Cacti for statistics + mailgraph and pflogsumm
SVN server
OpenSSL for web servers and for emails
No tools can port this software on centos 7.
Kernel 3.1 is nothing more than the core that feeds all the new features, its head is Linus Torvalds, so no need to argue on it,
one of the best piece of software ever written.
Let's start analyzing the other new cool features.
SystemD is so fast and so asynchronous that it breaks more than it fix.
Changing scripts from initd to systemd is quite easy and it requires small effort.
The real problem is in the asynchronous start.
It took me a day to understand why postfix doesn't start with systemd while IPV6 networking is enabled.
In few words postfix started before the system got an IP and this breaked all.
Systemctl is no way good as ntsysv, ntsysv give you all the info you need with small effort,
it gives you what services are present, what are enabled, what are disabled and give you info on the service by pressing F1.
systemctl bla bla bla bla to do all this things
systemctl start postfix.service
service postfix start
I absolutely prefer the initd style.
FirewallD refresh the way you use iptables and it's good and bad at the same time.
It is useful if using IPV4+IPV6 since it can manage both IP version with the same configuration, no needs for two config files and two different rules.
The bad is that you need to study a new style to do always the same things.
FirewallD brings "the concept of zones", ok, I like it on my windows pc, I don't need it on my server.
EL7 repository lacks too much packages, EPEL is quite empty and this is not good.
PHP is compiled with a more restrictive policy, it blocks the use of TLS socket while using self signed certificate.
The switch from MySQL to MariaDB is completely painless.
Never spent so much time to switch from a major version to another, in place upgrade? ahahah