Re: Help choosing hardware

[Craig Puetz <puetz@cedarnet.org>]

Alex Perry wrote:

> lsorense@csclub.uwaterloo.ca wrote:
>>If nothing else an opteron runs the i386 version of debian faster
>>thananything else, and if you need 64bit support, it can do that too (I
>>believe sarge does have amd64-libs and an amd64 kernel that can be used
>>on i386 sarge to run 64bit programs when there is a need for 64bit).
> 
> The 64 bit kernels are completely stable, as far as I know, so I would
> suggest you use a 64 bit kernel and either a 32 bit or 64 bit userspace.
> 
> If the two userspaces are installed both as boot options and as chroots,
> you can very quickly compare them in performance terms every time you
> make a non-trivial change in the application architecture.  If you keep
> the data and logic stored in an architecture neutral repository that is
> on a separate filesystem tree from the rest of the system binaries, you
> can switch between 32 bit and 64 bit production environment in seconds
> by stopping services in one chroot and starting them in the other.
>
 This is easy, and correct, but:
        Be very careful if you put configuration information into the shared
neutral repository (such as in hidden directories under "home"
directories). You can be working along, confident that you can revert to
the stable, production system without any problem. When you do, you find
that your supposedly untouched "stable" system is as broken as the one you
were working in due to configuration changes you may have accidently stored
(yes, this is from experience). If you have "special" user directories that
are to support applications, or processes, I would place copies with both
the 32bit and 64bit filesystems.

Craig

> You're describing a standard server style software stack, such as has
> been running on 64 bit architectures for years, and not something that
> uses code originally written for x86 desktops and is only just porting.
> Debian's AMD64 is a pure port, so I suggest it is just as reliable as
> running Debian's Sparc 64 bit support for the same source versions.
> The complications happen when you try to go biarch or have 32 bit
> libraries integrated into the 64 bit system, but you don't need that.
> 
> Hope that helps,
> Alex.