Today, Linux is in the core of companies IT departments. Along with the development of a vision on the use of Linux, companies tend to select one Linux distribution for all servers using Linux. That is because it is much easier for IT departments if they don't have to manage different distributions with sometimes small but important differences. Also, standardizing on one Linux distribution makes the purchasing process a lot easier....
But before being able to standardize on one Linux flavor, the old Linux distribution has to replaced with a new one. So, what is involved in this procedure?
In a migration process from one Linux distribution to another, there are some aspects that should be taken care of. First, there is a technical aspect.
You cannot just copy the configuration files of your Apache server to another Linux distribution and expect it to work. If for instance you compare the way the Apache configuration files are structured on a Red Hat server, this is completely different from the way they are organized on a SUSE server. And this is just one example of how services may be configured differently on different Linux distributions.
So if you cannot just copy files from one machine to another, there needs to be a clear plan for how to do it. This plan can consist of using the appropriate tools, but it may also mean that you just have to sit and work out the plan with a consultant to make an inventory of what exactly you need to do in the migration.
Apart from the services, there is the way the operating system itself is working. On Ubuntu, Upstart is used to start services and that is very different than the Init based startup procedure that is used on Red Hat. This is especially is important if you have applications on your server that aren't a part of the distribution itself. You need to ensure the application is compatible with the way the new distribution wants to handle it. To be able to judge that, you may first have to send your IT staff to a training course, after which you can analyze the current server and the new server from this perspective also.
Pay for one distribution, use two
Apart from the technical perspective, there is also a financial angle. If migrating from one Enterprise Linux distribution to another Linux distribution means that you still need maintenance on both for a time, that would mean that you need to pay twice. So when making the switch, for example from Red Hat to SUSE, or in the opposite direction, you need to talk to the new Linux vendor and see if he can help you. For example, Novell has a solution where they can offer patches for Red Hat servers that need to be migrated to SUSE under certain conditions. This solution is quite unique, because it means that Novell modifies all patches that are supplied by Red Hat, to be legally compliant so that they can be applied to the Red Hat server before all of its services are transitioned to SUSE.
Of course there is another approach to this problem as well, and that is just moving over to a distribution where you don't have to buy maintenance in order to download and install patches. Ubuntu Server in its LTS versions for instance is free, you'll just pay Canonical, the company behind Ubuntu for the support that you really use
But there is more to managing patches than just the financial part. There is an organizational aspect as well. You might be using a solution like Canonical Landscape, Red Hat Satellite Server, or Novell's Subscription Management tool for management of your subscriptions.
Some of these tools are just made to manage the "native" Linux distribution of the tool. Other tools may be capable of managing more than just one distribution. Before starting the migration plans, it's a good idea to investigate the solutions offered by your new Linux vendor, as it is easier to manage patches from within a single tool for both distributions.
Migrating Linux is mostly about migrating services. To do this properly, there are two approaches. You can find out yourself what needs to be done, or you can use tools that analyze this for you. Apart from the services involved, migrating Linux is also about smoothly transitioning from one environment to another environment, without involving double work for your IT environment. If you have the appropriate system management tools in place, they can be very helpful. Finally, depending on the Linux distributions that you were using and that you are going to use, these might be a financial chapter as well. Check this with the new vendor of your choice. This vendor is going to earn your money and may be more than willing to help.
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ABOUT THE AUTHOR: Sander van Vugt is an author and independent technical trainer, specializing in Linux since 1994. Vugt is also a technical consultant for high-availability (HA) clustering and performance optimization, as well as an expert on SLED 10 administration.