Diskless Linux cluster with Linpack benchmark software

Linux, Networking, Thermal testing:

There are basically two ways of setting up a -diskless- Linux cluster, one is by preparing an image for the diskless clients which is resting on the server and the second way is to directly share the Linux file system of the server. Here, we follow the second way.
Linpack is a benchmarking software which can also be used very well to create thermal stress to the machine, like for testing in a temperature chamber, if the parameters are adjusted well.

So you can picture one server with an HDD and the clients (here only having command line) seeming to be independent workstations. You can also use the Linux Desktop GUI on the clients, in which case you have to adjust the xorg.conf file in the /etc/X11/ folder (here OpenSuse Linux). Note: You can put the xorg.conf file there even if there is none for standard (in more recent OpenSuse versions).

Diskless Linux and Linpack PowerPoint presentation
Diskless Linux and Linpack HOW TO PowerPoint (v0.6)
Diskless Linux and Linpack ... startup cluster

Double-booting Centos and openSUSE

I had installed openSUSE 11.1 on hda7 (root) and hda8 (home). The partition hda1 was empty, as it once had contained a Windows installation which was now obsolete. I removed the partition (you can use fdisk to do that of course***) and then installed CentOS 5.3 on hda1. Swap partition is hda6 but it seems only openSUSE is using that one right now (must look into that).

I took over default settings for the installation and finally only CentOS was shown by grub. However you can easily make Suse bootable as well:

1. Mount the Suse partition from a CentOS terminal:
for me that was (being root):
#mkdir /suse
#mount /dev/hda7 /suse
#vi /suse/boot/grub/menu.lst

Now leave the editor vi open and open a second terminal being root as well:

#vi /boot/grub/menu.lst

Copy what it says about the Suse standard boot entry from the first terminal and paste that into the second terminal. Now you have two boot entries. Should work fine.

*** or remove it during CentOS intall. Do not reuse the Windows partition.

Troubleshooting: After doing an automatic kernel update on /dev/hda7 (openSuse), the system could not bootup Suse anymore. Reason: the copied entry in /boot/grub/menu.lst (on the CentOS partition /dev/hda1 and not on the Suse partition!) was not updated automatically and so the VMLINUZ-x.y.z file could not be found.
Remedy: Bootup CentOS and correct the entry, taking /suse/boot/grub/menu.lst (that is /dev/hda7) as a blueprint.

Suse's Boot problem (openSUSE 11.2)

OpenSUSE 11.2 on a motherboard with (disabled) RAID function and a little unused extended partition (besides the usual Linux partitions) could not bootup after installation. Reason was, openSUSE was writing the boot info into the extended partition. Repairing with Suse's repair function was no use. When re-installing I clicked on the overview screen, where you see software packages and partitions on the boot section and clicked on the boot manager location (forgot the exact name, but it's easy to find) and then I saw "Boot from....extended partition" was selected by default. I changed that to "Master Boot Record (MBR)" and everything was fine.

Ah no, those are not from openSUSE. Sorry. But we really needed a pic in this blog.

Smart Package Manager for openSUSE 11.2

Actually this is too easy to write down, but I hadn't thought about it for a few hours and was a bit surprised it really worked, so...

Presently (Nov 2009) openSUSE 11.2 is out, but the Smart Package manager is not part of the distribution and a channel list (the repositories are being called channels in Smart) is nowhere to be found. Well, as a temporary solution I proceeded as follows: I simply took the 11.1 repositories and change the path names to 11.2. It does not always work and if the channel in question does not work yet, I disable it and wait patiently until the site I want to take it from finally supports 11.2.



So if you do this be VERY CAREFUL not to get an unstable system by taking wrong version repositories, carefully change each channel's path from .../11.1 to .../11.2 (check each channel carefully) and enable it ONLY if it works. Make sure not to enable any 11.1 channels without changing the path name. Again, including an 11.1 channel for your 11.2 system could be disastrous.

So, first include this Smart repository into Yast:

http://download.opensuse.org/repositories/smart/openSUSE_11.2/

... so you open Yast2, go to the software repositories and call the new repository smart, enable HTTP Protocol and the Server name is "download.opensuse.org" without the " and the directory on server is "/repositories/smart/openSUSE_11.2/

This allows you to install Smart and Smart-gui.

Next, change to a shell, be root user and bravely type:

smart channel --add http://xadux.eu/smart-channel/opensuse111-smart-repository

and confirm all channels you like. Note: There is no "opensuse112..." repository presently (Nov 2009). You can try out first if there is by the time you read this posting. If there is you are done.

Otherwise, edit the channel of the Smart package manager and enable only those you need and change the path names to the new version 11.2. Again: if they don't work, disable them. And do disable all channels which you hadn't change yet.

NEVER enable a channel before changing the file path to 11.2! Otherwise you can spoil your system.

Works for me as a temporary solution...

SSH from one Linux box to another (openSUSE)

Short manual how to go with a secure shell from one Linux box to another, one running openSUSE 11.2 and one running 11.1 (there is a little difficulty with openSUSE 11.2, you have to enable sshd first manually).

LINK to pdf (HERE) <--------- click on the left hand side of the arrow

Windows 2003 Server / 2000 Prof. dual boot machine

I had Windows 2003 server running twice on a box, on partition C and E with D in between being for data. No problem, the Windows boot menu comes up and I could select which one I wanted.

Now there is this old application which needs Windows 2000, and so I installed Windows 2000 on D. Not without saving all the boot-relevant files which are hidden on C. You know you have to click on Tools->Folder Options (in any window menu) in Win XP or 2ooo/2003 and then select View and then uncheck "hide protected system files" or check "show hidden files and folders" to see them, right? So I saved all the hidden files I could see then, most importantly the boot.ini file, in a folder C:\serverboot to be able to restore the Server bootup. That was necessary because installing an older Win OS over a younger one will make the more recent installation unbootable.

Ah yes, do NOT save the pagefile.sys file, it is large, protected and absolutely not what you need.

So in deed, Win2000 came up with a boot menu showing all three installations now (2000 prof. and two times 2003 server) but could only boot into Win 2000. No problem at all, that was to be expected, because installing an older Windows OS over a younger one leads to this effect.

I saved the whole bunch of hidden files on C:\ one more time, in a folder called C:\2000boot and then copied back the files from C:\serverboot while still running Windows 2000. No problem at all, I saw my old server menu with 2003 server on C:\ and 2003 server "experimental" on E:\ and could boot both. The new Windows 2000 installation was totally ignored of course.

So what do I do when I want to switch back to Windows 2000? I boot up the system as Windows 2003 server, copy the boot files out of C:\2000boot back on C:\ and then reboot. Easy. With both sets of boot files I can always switch back and forth.

The astonishing thing was the Win 2003 server boot files not being able to boot into Win 2000. I tried it and made a manual entry for the Win 2000 partition on D:\ (which has reference 2 in the boot.ini file) but it could not boot up. Also copying the original Win 2000 boot.ini file (which mentions all 3 OS) did not help. But this is the way you get Win XP and Win 2000 boot after you installed 2000 on an existing Win XP system. Obviously XP is downward compatible with 2000, but 2003 server is not downward compatible with 2000.

Summary:

- If you want to install Win XP and Win 2000 on one system, best way is to first install Win 2000 (say in C:\) and then Win XP (say, in D:\). You will have a lovely dual-boot system.

- If you do it the other way round (XP first, then 2000) you have to save the hidden boot files on C:\ in a folder (called C:\xpboot or so) and then copy all but the boot.ini file back after installing 2000 to get a nice dual-boot system as well.

- If you install Windows 2000 and 2003 server on one system, you always have to save both sets of hidden boot files on C:\ in two folders (C:\2000boot and C:\serverboot for example) and then you can switch back and forth.


NOTES:
What is true for XP and 2000 should also apply for Vista/XP and Win7/Vista.

If you install two OS on your computer (or even two instances of the same OS), always use one partition each. Never install twice into the same partition, such a dual-boot one-partition system will be unstable.

openSUSE 11.1 as a router

Use openSUSE 11.1 to share an Internet connection to other boxes, have it issue the IP addresses (or use static ones) and, of course, its enabled firewall will shield your clients attached to it quite a bit. Early draft of the manual, correct, but no pics and likewise.

http://papers.teichert-online.de/useOpenSUSEasRouter_v0.1.pdf