Talking about ease of maintanence / software support does it matter what version of linux i386 or x64 version is installed?
Server obviously is 64 bit however i wonder if living with 64bit OS would add any more pain when it comes to finding software updates and software installation.
Linux distro in question is Centos 5, hardware is basic VPS with 384MB.
For a server just use the 64bit operating system
Back in 2006 there were problems getting device drivers.
You're talking about a Virtual Server so that certainly won't apply to you.
All the software you want to run will work on the 64 bit operating system just fine
The links below are the relevant sections from the Wikipedia page http://en.wikipedia.org/wiki/64-bit
"In x86-64 architecture (AMD64), the majority of the 32-bit operating systems and applications are able to run smoothly on the 64-bit hardware."
With only 384 MB RAM, it's not exactly clear to me why you'd want to go the 64 bit way. You obviously do not need a 64 bit capable OS to address that amount of memory. You may even see increased memory usage due to using 64 bit (for one thing, all pointers are now 64 bits instead of 32). You probably won't gain by using a 64 bit os, except for what you can read in the links provided by giaresu... .
If the hardware is 64bit capable then go for a x86_64 installation. Almost all the packaged software is open and compiled for that architecture. The biggest problems used to be the binary plugins for the browser but now there are 64bit versions of both Java and Flash Player (although this one is still a bit experimental).
For normal usage you won't have any problem, but if you depend on some (closed) 32bit-only application you may want to stick to a 32bit installation. Note that most distros in their 64 version also provide a subset of their libraries compiled in 32bit mode so you can still run 32bit-only application provided that you can find all the packages to satisfy the dependencies (but - at least with Debian - it's pretty easy to convert a 32bit .deb library to a compatibility package installable on the 64bit distribution)
The biggest issue with using a 64-bit OS is the wasted memory when using Java applications (Java is pointer-happy). You can mitigate this by providing developers with a 32 or 64 bit version of Java, and an explanation of the issues.
It's inconceivable to find software that won't run on the 64-bit system that will run on the 32-bit system. RedHat provides 32-bit compat libraries for everything.
Users who need to allocate more than 4GB (really 2 or 3 GB) of RAM will get very upset if they learn that you installed a 32-bit OS. Although I did have some users who used a few hundred megs of RAM unless a catastrophic memory leak occurred. They were very upset that we gave them 64-bit Java on a 64-bit OS - the whole system crashed (minutes of downtime) instead of the problematic application (seconds of downtime).
There are still some commercial apps that are only supported on the 32-bit version (as I discovered when I tried to deploy Kerio Mail Server 6.6.1 back in March-- 6.7.0 was released in May and is 64-bit compatible, so that's okay now). If you're planning on only running FOSS apps or a few commercial closed-source apps which are 64-bit compatible that's not so much of an issue.
The main pain point I've seen while trying to use a 64-bit linux OS is driver support for hardware. Assuming your specific hardware has good stable 64-bit drivers, I'd say go for the x64 version to help future proof your installation.
I have two quibbles about 64-bit Linux. Java and Flash. I use Eclipse and SQL Developer regularly, and getting them set up was annoying. Not impossible or terrible, but there was some extra work. I still don't have a reliable Flash plugin installed.
It depends.
As mentioned by others, some applications work better on 32bit OS vs. 64bit OS. The reverse is also true.
As mentioned by others, 64bit OS allows for more RAM access than even 32bit with PAE enabled, although PAE enabled OS can general access a lot of RAM.
What I have found, much to my dismay, is that the chipset/BIOS puts a limit on the maximum memory I can use. Even with 64bit Ubuntu, my system still can only access 3.2GB of RAM. I decided to return to the 32bit version to take advantage of better compatibility with some consumer applications
As ever it's always a question of what you need your machine/s to achieve. You may find it impossible to do what you need with 64-bit code for a variety of reasons but I always say that everyone should AIM to run in a 64-bit environment but to be very much on the lookout for reasons that would stop you from doing so.
I am currently running the 64-bit version of CentOS 5.1 without trouble. Unless you have a specific, staticly-compiled binary (or worse yet, a proprietary app), don't sweat it, just go 64-bit. The 64-bit environment is supported by most virtual machines these days.
