Hard reset on linux command line.

Linux is not Windows and if reboot fail you usually still connect by SSH and do something. This commands will show you how to remotely hard reboot machine.

Hard reboot mean that shutdown scripts will not run and machine reboot immediately without syncing hard disk drives, shutdown applications etc, it’s like hitting the reset button on your server.

 

echo 1 > /proc/sys/kernel/sysrq

echo b > /proc/sysrq-trigger

This commands enable sysrq and after this calls fast reboot. If you want to force shutdown machine try this.
Force shutdown

 

echo 1 > /proc/sys/kernel/sysrq

echo o > /proc/sysrq-trigger

This came handy, when I had a server that had some IO error and it can no longer read from disk, only few cached binaries into memory kept it running (kernel, SSHD, bash), I could still access the machine via SSH but can no longer do anything, forcing the reboot as mentioned above was my only resort, and it worked like charm…

Kernel 2.6.31 is out and rocking!

This weekend I’ve had some free time so I tested a new kernel on my suse 11.1 x86_64 system. I’ve been a beta tester for the kernel for some time and I was eager to test the final version.

There are plenty new features, the one I enjoy more are probably on the filesystem area but there is plenty to choose.

This version adds USB 3.0 support, a equivalent of FUSE for character devices used for proxying OSS sound to ALSA, some memory management changes that improve interactivity in desktops, readahead improvements, ATI Radeon Modesetting support, support for Intel’s Wireless Multicomm 3200 Wifi devices, kernel support and a userspace tool for performance counters, gcov support, a memory checker for unitialized memory, a memory leak detector, a reimplementation of inotify and dnotify on top of a new filesystem notification infrastructure, btrfs improvements, support for the IEEE 802.15.4 network standard, IPv4 over Firewire, many new drivers, small improvements and fixes.

You may see the hole list here:

http://kernelnewbies.org/Linux_2_6_31

I still didn’t do extensive testing but so far so good ;), although my kde4.3  seams to lag a bit, I’m not sure if this is from the new kernel or the changes I’ve done within KDE itself.

On the other end with server machines it works perfectly, i’m doing stress tests on two virtual servers and memory usage / IO times / CPU usage.

On the test i’m using two opensuse 11.1 x86_64, one as 2.6.27 kernel version and the other 2.6.31, same amount of memory and 2 cpu each on the same host. Hope to have some more data in a few days and then post the results (cacti graphs) here if they are relevant.

So, what are you waiting for… TRY IT

Cheers

Pedro Oliveira

Kde 4.3 – Innovation or just patching?

Recently I upgraded my KDE version 4.2 to the 4.3 and I’ve been using it for a few days now. As said before I don’t mind using betas and do some testing, but as with everything there is an exception, in my case it was KDE, I used the first KDE4 betas and come back to 3.5 then used the 4.1 when it was stable, then 4.2 and tried the beta 4.3… once again came back to the 4.2, now that is stable I’m using version 4.3, and for the first time in KDE4 I can say it’s stable. In my opinion KDE4 was released way to early, and although usable it was needing serious work around it. I’m a Linux user with several years of experience and didn’t have much trouble using it, but for instance my wife would go crazy, so till KDE4.3 she was using KDE3.5.

What changed in this last version of KDE that made me upgrade all my machines to KDE4.3?

The KDE community has fixed over 10,000 bugs.

Implemented almost 2,000 feature requests in the last 6 months.

Close to 63,000 changes were checked in by a little under 700 contributors.

If you want to read more about it just check this link.

All this made KDE4.3 more user friendly, more reliable, more polished and prettier.

So, what more can I say about it? JUST INSTALL IT AND GIVE A TRY you won’t be disappointed.

In conclusion is there innovation or just patching in KDE 4.3? Definitely both, there’s hundreds of new features and even more bug fixes. Both are equally important and KDE really need this ultimate push to be the ultimate Desktop Manger.

Cheers and see you next time

Pedro Oliveira

ps – bellow there are the install instructions and a vid of kde4.3 in action.

If you need help to install it just check the install instructions (from www.kde.org):

Debian KDE 4.3.0 packages are available in the unstable repository.

  • Fedora
    • Rawhide development repository, however the packages there may depend on other Rawhide packages and are therefore not suitable for installation on previous releases.
    • Unofficial Fedora 11/10 packages are hosted at the kde-redhat project.
    • Kubuntu packages are available for 9.04. More details can be found in the announcement on Kubuntu.org.
    • Mandriva provide packages for
2009.0 i586 2009.0 x86_64 2009.0 SRPMS
2009.1 i586 2009.1 x86_64 2009.1 SRPMS

Please refer to README to more information.
For Mandriva Cooker ( development ) users, 4.3.0 is will be available at cooker repositories.

openSUSE packages are available for openSUSE 11.1 (one-click install), for openSUSE 11.0 (one-click install) and for openSUSE 10.3 (one-click install) and openSUSE Factory (one-click install). A KDE Four Live CD with these packages is also available.

Magic Linux KDE 4.3.0 packages are available for Magic Linux 2.5. See the release notes for detailed information and the FTP tree for packages.

QOS – Service with quality using MasterShaper

QOS – “Quality of service” – what a fancy name for somethings that will allow you to manage the available bandwidth for your servers/pcs/equipments. Usually setting up QOS is not “so fancy” to setup and manage. At work I had to setup a QOS for a custumer and didn’t want to be writing rules on my own so I searched a bit and found MasterShaper.

You can read more about it here.

Lets imagine that you want to allow p2p on your network but you don’t want to waste all your bandwidth on that kind of traffic, after all you still need bandwidth for your VOIP, http, and mail traffic.

To setup this I’ll be using CentOS and Mastershaper.

After installing a VMware virtual machine with CentOS (default install with 2 network cards), I’ve setup apache, this time I didn’t use virtualhosts or any other extras as I just wanted to create a single purpose system.

To start I’ve concufigured 2 network interfaces (internal/external)

eth0 192.168.251.249 (external)

eth1 192.168.252.249 (internal)

After downloading MasterShaper decompress it to:

/var/www/html

Install pear and pear modules as described in MasterShapper docs.

And finally create the mysql database to support the installation.

I won’t get into install details (just follow the documentation), but in the end you be able to define schedulers, hosts and services with higher or lower priority and in the end you’ll also be able to monitor all this in a pretty web interface with some graphics.

Just don’t forget to install mysql support in php, and pear, you’ll also have to configure sudo but in the end just read the documentation in mastershaper it’s very good.

Rsync or Bacula?

That was the question posed on linkedin:

Rsync or Bacula?

A short answer and a middle point:

BackupPC

It can use rsync with all its functionalities, you get a web interface for management,compression, pooling, multiple schedules, differential/incremental/full backups, win a lot of disk space and a security interface.
I use it for my home servers as well for my companies one (managing more or less 50 servers (windows/Linux) and it works like a charm.
The Best of it… it’s open source and have a lot of community support for it.
Cheers,

Pedro M. S. Oliveira

Ps – if you can run it over solaris with ZFS… even better 😉