Category: Centos

Booting Centos 7 with newer 5.x kernels fails with Realtek ethernet interfaces

If you have the problem described for example here, you can’t boot with newer ElRepo-kernels because the kernel driver für your Realtek ethernet card ist not loaded into the initrd environment, you can add them into /etc/dracut.conf

add_drivers+=”r8169 realtek “

and rebuild the initramfs with something like

dracut -f -v /boot/initramfs-5.8.5-1.el7.elrepo.x86_64.img 5.8.5-1.el7.elrepo.x86_64
grub2-mkconfig -o /boot/grub2/grub.cfg

Samba 4.10 exiting quietly while Samba 4.9 works

On my Centos-7-server I’m compiling samba as a file server. This worked well up to version 4.9. After 4.10 was released, I did my compile routine, started smbd and it exited immediately and quietly. Even with debug output and in a debug build there was no conclusive output. Looking through the samba sources there where some points where the smbd server process exits without printing some message. so I started instrumenting this exits and working up the call tree to the point where the lock dir gets set. I did not change this via configure, so it was the default /var/lock which worked well for version 4.9, but version 4.10 and up need the configure option --with-lockdir=/var/run/lock/samba to run, why I did not fathom. Now everything works again.

Installing MyMedia For Alexa on Centos / MyMedia For Alexa auf Centos installieren

Some German first: Was Alexa definitiv fehlt, ist die eigene Musik-Bibliothek abspielen. Wer allerdings mit der Amazon-Bibliothek oder mit Prime Music Erfahrung hat, weiß, dass das nur wenn man viel Humor hat und auf Aussprache-Übungen steht ein Spaß ist. MyMediaAlexa löst auf jeden Fall das erste Problem: Es erlaubt, die eigenen mp3s mit Alexa abzuspielen. Dazu braucht man einen Server, der auf die Musik Zugriff hat, einen Alexa-Lautsprecher, die Bereitschaft 5$ Jahresgebühr zu zahlen und Geduld, weil der deutsche Alexa-Skill noch nicht veröffentlicht ist (aber im Beta-Test, das kann ich sagen).

Now back to English: If your home server is 64 bit Ubuntu, Debian or Arm-based, you can go to their homepage and download the installation package and do whatever you folks do with them. If you are rpm-based like me on Centos, it is a little bit more involved to get the MyMediaForAlexa-server up and running. Download the Debian-package, deb-files are simple archives, so ar -x mymedia_1.3.58.0-1_amd64.deb will extract it. Relevant is only data.tar.xz which a tar -xf data.tar.xz boldly extracts. Now, cd to opt/mymedia, create a directory /opt/mymedia and move and MyMediaForAlexa from the first to the second path (Note: The path is hardcoded, nowhere else it will work). Then edit the file mymedia.service.template and replace USERTEMPLATE with the user the service should run under. I’ve choosen root, but this may be a suboptimal solution. Then copy the file to /usr/lib/systemd/system as mymedia.service. Some house-keeping: systemctl daemon-reload; systemctl enable mymedia; systemctl start mymedia. Direct your browser to http://localhost:52051 (or the IP of your server if it is headless; you may need to tunnel via putty and ssh to your server, I’m not sure if it is necessary, but I’ve done it this way). Now you should be able to connect your Amazon account to MyMedia. At this point I had on Windows as well as on Linux an error “no internet connection”, killing and restarting the service resolved this.

Some hints: If there are problems, the error messages on the console offer from time to time to download logs. This is most helpful, look there if you have issues. As shortcut, direct your browser to http://localhost:52051/logs to download them directly. If your music is on a samba share visible to your windows server, you have to first connect the share with MyMediaForAlexa even if there is already a drive connected.

Centos, Kolab and php-fpm

If you want to simultaneously use other PHP-versions or simply like to have the additional performance and manageability FastCGI Process Manager (PHP FPM) is the way to go. Basic receipt is:

yum install php-fpm
; Edit /etc/php-fpm.d/www.conf Listen-Port to 9054
systemctl enable php-fpm
systemctl start php-fpm
rm /etc/httpd/conf.modules.d/10-php.conf
; Edit in /etc/httpd/conf.d/ the websites you want to use PHP 5.4 FPM
            SetHandler "proxy:fcgi://"
apachectl graceful

Generally php-directives in conf and .htaccess-files don’t work with FPM. If you get errors on restarting httpd you have to remove those statements and either try to live without them or add .user.ini-files, add it to the global settings or use SetEnv-statements.
Kolab is tied to PHP 5.4 on Centos 7 and also needs some tweaking to work with FPM.

Continue reading “Centos, Kolab and php-fpm”

Pimping Centos 7 Part 3: btrfs-progs

Having a current mainline-kernel (Part 1), and using BTRFS (I would not recommend doing likewise, and RedHat won’t continue to support it) having the versionally fitting utilities would be great.

First step: Setting up everything (this list may not be complete, check configure output in step 2 that everything needed ist available)

yum remove btrfs-progs
yum install libuuid-devel libattr-devel zlib-devel libacl-devel e2fsprogs-devel libblkid-devel lzo-devel asciidoc xmlto
git clone

Second step: Script file

git pull
make && make install && make clean

Execute by executing

scl enable devtoolset-7 ./

The files get installed into /usr/local/bin, check by which btrfs and btrfs --version that everything worked out.

Pimping Centos 7 Part 2: Devtoolset-7 C/C++

Centos 7 comes with gcc 4.8.5 which is quite dated. Software Collections have a build for Devtoolset-6 with gcc 6.3.1. Devtoolset-7 with gcc 7.1.1 is in the making. So why don’t we snatch it right from the build server? Be sure to check if newer builds are available by sneaking down the URL and adjusting the URLs accordingly

yum install

As always with Software Collections, you have to enable it explicitly to use it:  scl enable devtoolset-7 "gcc -v". I’ve created a one-line shell script named

scl enable devtoolset-7 ./

which simply calls another script named with Devtoolset-7 enabled to do all the work (don’t forget to chmod +x both). Next time we put this to use.

Update 2017-10-11: The C++ toolset arrived at the Software Collections Server. No need anymore to grab it directly.

Update 2017-10-29: New version 7.2 is on the build server:

yum update[/pre]

Pimping Centos 7 Part 1: Kernel

Centos comes with kernel 3.10.0-514. This is not a problem securitywise, as RedHat patches security and some bug fixes into its distribution.

If you have nothing to lose but want to live on the bledding edge and want support for current hardware like dvb-tuners, then Elrepo is for you: Either long-term-support/lt or absolutly current kernels (mainline/ml) yum’ed directly to your server (and for years on mine with no issues). At the moment kernel 4.13.3 is current, within a day or two after release of kernel 4.14.0 a simple yum --enablerepo=elrepo-kernel update should install it.

rpm --import
rpm -Uvh
yum --enablerepo=elrepo-kernel install kernel-ml



Centos, Owncloud and PHP 5.6/7.1

Centos 7 comes with PHP 5.4, securitywise this is not a problem, fixes get backported by RedHat, but Owncloud X (and likewise Nextcloud) need at least PHP 5.6. And naturally other web apps may also gain from newer PHP versions.

There is a more or less official way to have newer PHP versions on Centos and RHEL, Software Collections. There is PHP 5.6 and PHP 7.0. A slightly less official way for a current version is the Remi repository with PHP 7.1.

The Software Collection-way of installation is parallel installation, this means the newer PHP ist installed side by side to the system’s version (look in /opt, /etc/opt and /var/opt paths) and is only used if called explicitly. This is very clean but not very practical. You easily find howtos on globally changing the system’s PHP Version to the new one, especially for the Apache httpd Server, the main consumer of PHP. Remi also a has “replacing” way of installation.

But what if other web apps like Kolab won’t work with anything else than PHP 5.4?

Continue reading “Centos, Owncloud and PHP 5.6/7.1”

Linux and Plextor SSD

I own a small Linux Server with a 64GB Plextor M3/M5/M6 Series SSD, first a PLEXTOR PX-64M5M and now a PLEXTOR PX-64M6M. Both drives had firmware version 1.03 and under stress (for example btrfs balance start /dev/sdb) I got loads of error messages like

kernel: ata3.00: device reported invalid CHS sector 0
kernel: ata3.00: exception Emask 0x0 SAct 0x7ffe00 SErr 0x50000 action 0x6 frozen
kernel: ata3: SError: { PHYRdyChg CommWake }
kernel: ata3.00: failed command: WRITE FPDMA QUEUED
kernel: ata3.00: cmd 61/00:48:48:c4:1b/02:00:07:00:00/40 tag 9 ncq dma 262144 out#012 res 40/00:00:00:01:80/00:00:00:00:00/00 Emask 0x4 (timeout)
kernel: ata3.00: status: { DRDY }

Continue reading “Linux and Plextor SSD”