[CentOS] i386 or x86_64 installation

Mon Jan 22 17:09:27 UTC 2007
Peter Kjellstrom <cap at nsc.liu.se>

On Monday 22 January 2007 17:05, Matt wrote:
> What are advantages of 64 bit OS anyway?  I was thinking with i386 the
> max RAM you could have was like 4 gigabyte or something?  64 bit
> allows quite a bit more, right?

You can have alot of RAM even in a 32-bit system. However, there is also the 
issue of efficiency and applications being able to actually use alot of 
memory. Here are some random bits of information on the subject:

* you can have alot more than 4G on 32-bit with pae (hugemem kernels)
* ...but, already at ~900M 32-bit has to start using highmem
* ...which can cause problems for (old and badly designed) applications 
already at ~900M
* 32-bit EL kernels have 4K kernel stacks, 64-bit has 8K, affects eg. XFS

> I am upgrading a very heavilly used email server to a AMD64 dual core
> with CentOS.  I am staying with i386 since the web GUI we use lists
> 64bit support as beta and I do not want any problems.

Not a bad choice, software functionality is probably one of the biggest 
differences between 32- and 64-bit.

/Peter
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