[nflug] AMD64 Debian 'Etch' Stability

[Ken Smith]

On Tue, 2008-06-10 at 13:46 -0700, David J. Andruczyk wrote:
> 64 bit  OS's are needed for only the few reasons:
>  1. you have more than 4 GB of ram, AND you want your processes to be
> able to address all of it (Databases,  high performance
> virtualization,  VMware ESX, Xen, etc)
>  2.  You need very large virtual address space (niche applications,
> large datasets, distributed dataset processing)

3) You deal with a significant-ish amount of *data* (not total size of
all your data, the size of one piece of your data) that overflows
32-bits.  Quick example to illustrate - we can create files that are
larger than 4Gb.  That means what the operating system uses to store the
value of the size of the file needs to be bigger than 32-bits.

If you do a significant amount of manipulating 64-bit quantities because
the things you're manipulating overflow 32-bit quantities then the
64-bit processors can be a win.

And that at least in part answers the question someone else had about
why you might want a 64-bit processor in a machine that is physically
capable of only having 2Gb or 4Gb of memory.  There are other reasons
you might consider this.  In some large sites it's more of a pain in the
butt than it's worth to for example support both 32-bit and 64-bit
systems (for example perhaps a University where you tend to build a lot
of software yourself and put it all in an NFS-mounted partition
named /util which all your machines mount :-).  If you've made the
decision to take the plunge and support 64-bit its nice to be able to
run even small machines 64-bit so they can take advantage of the
shared /util.

-- 
                                                Ken Smith
- From there to here, from here to      |       kensmith at cse.buffalo.edu
  there, funny things are everywhere.   |
                      - Theodore Geisel |