If you're considering buying 64-bit blade servers, there are many good reasons to run Linux on them. If that's your game plan, I applaud you, but I must advise you that this marriage will work only if the two partners -- server and distribution -- are well-matched.
Therefore, like a marriage counselor, I offer these guidelines for choosing blade servers and Linux distributions that will be compatible.
Choosing your hardware
If you already own a blade server that is running on a different operating system, you may skip ahead to the next section on distribution selection. However, you're probably going to buy more blades soon; either way, you could glean some info from this advice.
Not every server manufacturer makes blade servers today, but I bet that many more will have that offering in the next year or so. Currently, IBM, HP and Dell sell the most servers, in general, and the same goes for blades. Choosing from their lines is just fine, but don't disregard blades from smaller vendors. Often, the smaller vendors offer more personal service and blades that have features tailored for certain niche uses, one of which might fit the bill for you.
The hardware you choose is going to be crucial. One drawback with blade servers is that there are no standards at this time. Several blade server manufacturers have been trying to create industry standards since 2003. As of this writing, the standards are not there and may still be years away. Your choice of hardware does mean that you are willfully subjecting yourself to vendor lock-in. If you choose Dell, IBM, or HP, make sure you are comfortable with the price, service warranty and any other factor that is important to you.
Blade servers come at various prices, numbers of blades per unit, warranties, etc. Some will even come with a Linux distribution pre-installed. For example, Red Hat Enteprise Linux 4 (RHEL4) and Novell SUSE Enterprise Server 10 (SLES 10) can be pre-loaded on Dell PowerEdge, HP BladeSystem and can be preloaded on IBM BladeCenter blade servers.
Looking for more Linux distro options? Verari Systems can put RHEL4, SLES 10 or CentOS, a free Linux distribution, on its VS1205 Blade Server. HP used to pre-install Debian Linux, but I can't find any documentation saying this still happens. Every so often, a vendor will support a relatively obscure -- in the corporate world, at least -- distro, such as TAFusion's MEPIS Migration Server; but frankly, the lifespans of such preloads are not long-lived. Outside of the U.S., you'll find more distros loaded onto blade servers of various stripes. I can't recommend them. It may be boring, but -- unless your company is in a niche market well-served by a certain Linux distribution -- sticking with Red Hat, SUSE or, perhaps, Debian is the safer route.
Getting the appropriate Linux distribution
The good news about Linux is that there is no shortage of choices. The bad news about Linux is that there is no shortage of choices. Some Linux distributions, such as SUSE or RHEL, offer paid support options directly from the distribution maker. Other community distros, like Ubuntu and CentOS, are free of charge and have many paid support options available.
Debian and Gentoo are two of the many fine distros out there that have no professional support readily available, but do offer robust communities and a few specialists out there who can support such distros. So, with all these different choices available to you, how do you decide?
In this case, however, you are choosing a distribution suited for a blade server. Obviously, you don't want to choose distros primarily designed for desktops. As great as they are, now may not be the time to install Freespire. Red Hat, SUSE, Gentoo, Ubuntu and others have server-specific installations.
SLES 10 and RHEL 4 are about equal in quality and support for blade servers, in my opinion. They are both optimizing for 64-bit systems and making alliances with the big boys of blades -- HP, IBM and Dell. Now, in some cases, the free CentOS may be fine, as it is based on the RHEL binaries, and they do a hell of job in developing this distribution.
If you're not running a huge operation, some free versions of Red Hat, SUSE or other distributions may work. I sometimes prefer free distros. For example, if you put a Dell blade server with a bow on it under my tree, I would slap Gentoo or Ubuntu on it. Why? I like Ubuntu's package management, and Canonical now gives me paid support options. Gentoo? Well, Gentoo is not for the faint of heart when it comes to installation and configuration; but once it is set up, Gentoo's Portage and Emerge make your life pretty trouble-free. Pain on the front end for an easy ride? Sweet!
Here are some other issues to consider when choosing distributions for blades:
- You will be running on a 64-bit system, possibly even a dual-core 64-bit system. Obviously, you have to make sure that the distribution is compatible with your hardware. Occasionally, the information is available from the manufacturer of the hardware, but check those specs carefully! In other cases, the distro will have a hardware-compatibility database, so you may have to do a Google research.
- Make sure your distribution can get the most out of your hardware. Some distros are not currently taking full advantage of 64-bit architectures. You're investing in a new type of server, one that promises superior performance, so make you get the most performance possible. Using a free distro that isn't optimized for 64-bit architectures isn't going to save you any money.
- Commercial Linux distributions have fees associated with them, and part of those fees get you added features, some of which will be proprietary. Read the fine print to determine how much value, in terms of add-on functionality, a Linux distro is offering for the cost.
- Support is the other thing you're buying with commercial Linux. I can download Gentoo from the Web at no cost. With the free download, I don't get commercial support, but I will get access to wikis, mailing lists and developers. This is support for proactive people who don't mind searching for it. With a purchased commercial distro, I get access to people who help me install, configure and support the distro in a blade environment.
So, how confident are you in your IT staff''s ability to handle or find solutions to its own problems? How much is your time worth? These questions will help you determine how much support you will need. It your staff is very familiar with LinuxLand, you could lean toward the free software side of the fence.
- Older releases of Linux are not out per se; however, if they were made in a 32-bit world, they are installable on 64-bit blade servers, but may not realize the full power of the processor. Most people may not notice, but if you are doing some heavy maths, you may note the difference in performance.
Creating a migration roadmap
You've worked hard to choose the right blades and distribution, now you're ready to move on to the putting them in your data center. Creating a stellar migration roadmap can prevent as many headaches as ibuprofen. Migration is about more than hardware compatibility, files, total cost of ownership and return on investment.. The next installment in my Linux-on-blade series considers those subjects and others crucial to successful migration planning.
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