CentOS versus Debian would be mostly personal preference unless you have compatibility issues with specification applications or control panels which exclude one or the other. Both OS's are fairly well supported though.
Regarding 32 bit or 64 bit you would typically go with 64 bit unless a lagacy application requires 32 bit. You should be best to go with 64 bit for a number of reasons though mostly related to performance.
- Donovan K Want to monitor and manage your customers Windows systems by Client software, web portal, or mobile phone?
Automated scripts, patching, and remote access too? Ask me how!
I find CentOS generally has more support in all respects, though Debian is a great OS too. I tend to go for Debian for low footprint installations and for personal stuff. Both are perfectly capable of running webservers.
I recommend clients to go with 64bit for addressing more than 4GB of ram. Which is useful down the road even though you need less than that now. Much better than reinstalling the OS down the road. I understand you can use PAE but, I personally 64bit makes things easier.
█Dynamic Concepts, Inc. • Creative Technology • Orange County • California
█Colocation • VPS • Dedicated Servers • Managed Hosting • SAS70 Type II Certified
█ProStores • Kerio MailServer • Web Design & Development
█Scott Lee • email: wht"AT"dynamic.com • http://www.dynamic.com • (949)215-1200
My 2 cents would be go with 64 bit CentOS 5.* , it seems as if CentOS has a larger support base, it works with cpanel, and is a bit more popular because of working with cPanel. Both are fairly comparable though
Firstly, there are PAE extensions so that you can use more than 4GB with a 32bit OS. However, each process will not be able to use more than 3GB. For a server environment however, this is very rarely an issue.
For some applications, 32bit will be faster and for others, 64bit will be faster.
32bit is faster when the application uses mostly 32bit, 16bit, and 8bit variables. Most network oriented tasks or applications will perform faster as 32bit. In particular, you will see much faster performance with routing, firewalling, etc as we are still using IPV4.
64bit is faster when the application uses a lot of 64bit or larger variables. This is simply because more data can be manipulated in fewer instructions. Databases usually tend to perform faster in 64bit for instance. There is also the advantage of extra sets of registers being available in the AMD64 ISA.
However, there are also disadvantages to 64bit. For instance, you essentially lose half your CPU cache, because even 32bit or smaller chunks of data will occupy 64bits of cache. The same applies to your RAM. Also, because data is moved around in larger chunks, you are more likely to exhaust your memory bandwidth as you are moving around data in larger chunks than you are actually using.
Anyway, so far as web hosting environments are concerned, go 64bit if you have databases that see a lot of usage, but otherwise go 32bit.
As for CentOS vs Debian, use CentOS if you need support for commercial applications, but otherwise go Debian. Debian has a cleaner design and makes more sensible decisions in a lot of different scenarios. Package management is also better, with dependencies and upgrades being handled better. There are more packages and also a larger variety of apt repositories available than yum repositories, which makes using less common apps much easier.
I would still take FreeBSD over either one of them any day though
ASTUTE HOSTING: Advanced, customized, and scalable solutions with AS54527 Premium Canadian Optimized Network (Level3, PEER1, Shaw, Tinet) MicroServers.io: Enterprise Dedicated Hardware with IPMI at VPS-like Prices using AS63213 Affordable Bandwidth (Cogent, HE, Tinet) Dedicated Hosting, Colo, Bandwidth, and Fiber out of Vancouver, Seattle, LA, Toronto, NYC, and Miami