Archive for the ‘SLES’ Category
July 9th, 2009 | 
Author: Very often it happens that I must give support to a colleague or a customer on a Linux machine.
It’s very difficult to spell all bash command I will use to check which could be the problem, especially by phone.
When I discover “screen” it was a revelation.
With screen http://www.gnu.org/software/screen/screen.html you should share a linux session with other people.
You should use screen by simply ask to the user you want to assist to type on the console the following command :
screen
So if you can connect to the machine (even with ssh) you should run the following command :
screen -x
to share the same bash session.
Hope this help
Bye
Riccardo
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In this post I am going to talk about a very particular piece of hardware, unique on the market at this moment and that should be very useful for virtualization or clustering purpose, with a very low budget.
This product is called DamVirtualOne.
DamVirtualOne is a modular server (not a Blade) and have some very interesting feature :
- Fully redundant hot swap power supply.
- Fully redundant hot swap Gigabit ethernet switches with failover.
- Fully redundant hot swap storage controller, with multipathing and failover support.
- Up to six (6) compute module double socket (for Intel Xeon 5400 or 5500 CPU family).
- Up to 96GB of RAM each compute module.
- Up to 14 HDD SAS.
- Up to two redundant external SAS connection to storage expansion or SAS device connection (i.e. Tape Unit).
But the more important things that lead me to write this post is that storage is shared between the compute module, but not as other Blade Server on the market right now, with DamVirtualOne you should create a Virtual Disk (similar to a SAN LUN) and share it between all compute module if you need it.
At this time only IBM Blade Center S should have the same possibility, but it’s a Blade server, not a modular server, and there is a big price difference.
I had the luck to test the DamVirtualOne for few days (a lot) and I’ve installed the following :
- VMware ESXi 3.5
- VMware ESX 3.5
- Red Hat Enterprise Linux 5.3
- Microsoft Windows Server 2003
- Microsoft Windows Server 2008
I’ve created some fully function, and very performance VMware HA and DRS Cluster, and some Linux Cluster based on RHEL, and a large number of my previous post was written based on the installation above.
The standard server virtualization or clustering best practices require shared storage to use all benefits of the technology and this lead to buy SAN, Storage array (tipically Fibre Channel) who is very expensive, difficult to maintain and create a very complex infrastructure.
So you should know why I’m so excited about DamVirtualOne, because it’s a “single package” that contains all things you need for virtualization or clustering purpose : servers, storage and network a real datacenter all in one.
With the maximum configuration this machine should support up tp two hundred (200) Virtual Machine !! And his price will be very similar to two or three phisical server (as you are useful to see) and a shared storage, so you should understand that is a beautiful “piece of iron”.
I truly believe that modular server is sometimes under valuated, but in my opinion there is an enormous potential in it and it will be beautiful if this post lead some people to find out a solution, cheaper than other more famous one, using this piece of technology.
You should found more details about DamVirtualOne at the following websites.
Feel free to ask, they will answer you !
Riccardo
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This post assume you have just installed SLES on your server, and that the server in correctly configured to access internet.
This post also assume that you want to create a mail server for the following domain :
- yourdomain.com
- yourdomain.net
In this post we’re going to create a local mail server, that support the two domain above (but could be more than those) based on Postfix and Cyrus-Imap, with IMAP, IMAPS and SIEVE support, optionally you could add also Antivirus and AntiSpam using Amavisd-New with Clamav and SpamAssassin, and we also going to provide a webmail using squirrelmail.
This post assume you want to put this mail server on your DMZ with an ip address 192.168.100.1 and that you want to permit mail relay from your local network (192.168.1.0/24) and from authenticated user.
All the tasks above will be explained in the rest of the post.
This post will explain hot-to configure a unique IP Address on multiple NICs (Phisical or Virtual) on SuSE Linux Enterprise Server (9 or 10).
This post assume you have a 192.168.1.0/24 network and that you want to assign 192.168.1.1/24 to your system.
To enable Xvnc on Suse Linux you have to uncomment one of the services instances in /etc/xinetd.d/vnc.
Then you had to enable Xdmcp logins in the file:
/etc/opt/kde3/share/config/kdm/kdmrc
Start or restart XINETD on try to connect to your machine with a VNC Viewer or whatever you’ve configured in the services section (i.e. WebBrowser, Java Applet).
