Re: [Linux-aus] Scaling

[Dan Shearer <dan@shearer.org>]

Leon,

On Wed, Jun 16, 2004 at 11:27:45AM +0800, Leon Brooks wrote:
> In a widely-reprinted article, you wrote:
> > the Linux environment does not scale up as well as Unix
> 
> I'm wondering if you could qualify this statement for our mailing list. 

I don't know the context of the original comment, but with a few
qualifiers that statement is reasonable. 

There are aspects of the rubbery term "scaleability" that are not
addressed by the fine collection of case studies you brought forward.
With appropriate qualifiers Linux cannot claim to be as scaleable as
Unix (but Open Source Software can, of course, so we win both ways :-)
For most enterprise uses there is no difference. For a small number of
companies with big wallets Unix is indeed more scaleable.

Examine the top-end SMP Unix machines from the major hardware shops and
look for a Linux equivalent, and you won't always find it. Sure, Linux
will run on a 64 processor uSPARC (I run it myself) but Solaris can
still do some tricks that Linux can't quite match, especially with
management and partitioning. That's changing, but Linux isn't at parity.

There is also the issue of third party support, which has been slow
coming to the very most expensive hardware and software. Buy a big
PowerPC box, put Linux on it, then ask for Linux support from all the
peripheral and software makers. Oracle have cracked but there are plenty
of others who haven't. Now try that with Linux/HPPA or Linux/uSPARC...
good luck even with Oracle :-) Large scale hardware has to have been
engineered with Linux in mind for very large companies to be interested.

Solaris, HP-UX, Irix, AIX and others can run most of the open source
software found on a Linux machine, and in some cases faster or more
reliably given the greater capabilities in some niche areas. In fact it
is not that hard to be just about completely at home in freeware on
these OSs if you put the right things in your path. Some people even
create their own Solaris distro to more closely match the LSB layout :-)

> How well does it stand up in the light of Linux being deployed in huge 
> clusters, huge single-image servers, and huge enterprises?

Your "huge single-image servers" argument looks a bit thin if you try to
argue that it is also "general purpose". I'm all for world domination so
long as we keep the record straight.

Your strongest argument is that much of the time nobody really needs a
single massive centralised server, which is almost the only area where
Unix still has an edge over Linux.

> A good reference for huge single-image servers is SGI's Altix:
> 
>     http://www.sgi.com/servers/altix/

Search for "'Solaris 10' zones" or "HP-UX Partitioning Continuum" to see
examples of things you can't do with an Altix, all things relating to
scaleability.

-- 
Dan Shearer
dan@shearer.org