[CS-FSLUG] Centos 7
Tim Young
Tim.Young at LightSys.org
Fri Jul 18 11:29:27 CDT 2014
To add some Linux traffic to the list...
Centos 7 has recently come out, and I am fiddling my way through
it. There are a number of things that surprised me.
MariaDB replaces mysql. MariaDB is a fork of mysql with some of the
original developers. Oracle is doing some things in a
not-so-friendly to open-source way with mysql, so a number of distros
are making this leap. MariaDB is supposed to be entirely compatible
with mysql, but will have some additional options that mysql does not
have.
systemd has replaced init / upstart scripts. So all the startup
scripts are quite different than they were before; living in
different directories and not using bash scripts to handle things.
systemd also does logging, so some distros will no longer have their
main logging go to /var/log and be textfiles. For people who have
made their own daemons in the past, there are some things systemd
assumes which may require you to make changes to your programs.
Centos used to use Lokkit, and are switching to firewalld. That is a
fairly substantial change. It is still iptables based, but it has
some odd ramifications for how things are done. Firewalld lets you
make changes to your firewall that are persistent or temporary.
Usually configuration is done by making changes to config files
instead of having them done programatically.
NetworkManager got put in the mainstream of Centos6, but is even
more-so in Centos 7. NetworkManager is supposed to do a better job
in dealing with mobility; when you change location, it adjusts the IP
configuration to match. This is great for laptops, but is a little
awkward for servers. Anyway, most of the network configuration is
now done with the "nmcli" command.
Which leads me to the depressing news that Centos has finally done
away with ifconfig, arp, netstat, mii-diag, route and a number of the
other "standard" network tools. You can still install the net-tools
package, but those commands have mainly been replaced by "ip." This
is a bit of a break because most of those other tools come default on
Windows computers (though with slightly different names) I always
looked really awesome when, as a Linux techie, I could sit at a
command-prompt of a Windows machine and determine what was going on
with their network faster than they could from the GUI. Now I will
need to resurrect my non-linux command-set to look so smart. Drat.
Centos also uses xfs by default. I have not run into anything with
that, but I know there are a number of things I used to take for
granted with the ext[2,3,4] filesystem that I will need to revisit.
They have also jumped kernels to the 3.x series instead of the
2.4/2.6 kernels. I have not yet begun to look into what the
difference in the kernel is.
I have really enjoyed how chrony keeps my VMs time to be correct. I
have no idea how well that will scale. ntp creates a lot of network
traffic, and suddenly having a lot of boxes checking ntp on a much
more regular basis may cause a lot of the ntp servers to go away.
But it is a very nice service to have running on my Virtual Machine!
Anyway. It will be interesting to see how Centos 7 pans out. For
myself, I will need to update all sorts of training materials that we
have built to incorporate all this new stuff.
- Tim Young
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