Re: tuning for AIX 5L with large memory - Mailing list pgsql-performance

fbsd@drivefaster.net (Dan Harris) writes:
> Christopher Browne wrote:
>
>>We have a couple of these at work; they're nice and fast, although the
>>process of compiling things, well, "makes me feel a little unclean."
>>
> Thanks very much for your detailed reply, Christopher.  Would you mind
> elaborating on the "makes me feel a little unclean" statement?

The way AIX manages symbol tables for shared libraries is fairly
astounding in its verbosity.

Go and try to compile, by hand, a shared library, and you'll see :-).

> Also, I'm curious which models you are running and if you have any
> anecdotal comparisons for perfomance?  I'm completely unfamiliar
> with AIX, so if there are dark corners that await me, I'd love to
> hear a little more so I can be prepared.  I'm going out on a limb
> here and jumping to an unfamiliar architecture as well as OS, but
> the IO performance of these systems has convinced me that it's what
> I need to break out of my I/O limited x86 systems.

It would probably be better for Andrew Sullivan to speak to the
details on that.  The main focus of comparison has been between AIX
and Solaris, and the AIX systems have looked generally pretty good.

We haven't yet had AIX under what could be truly assessed as "heavy
load."  That comes, in part, from the fact that brand-new
latest-generation pSeries hardware is _way_ faster than three-year-old
Solaris hardware.  Today's top-of-the-line is faster than what was
high-end three years ago, so the load that the Sun boxes can cope with
"underwhelms" the newer IBM hardware :-).

> I suppose when I do get it, I'll just experiment with different
> sizes of shared memory and run some benchmarks.  For the price of
> these things, they better be some good marks!

Well, there's more than one way of looking at these things.  One of
the important perspectives to me is the one of reliability.  A system
that is Way Fast, but which crashes once in a while with some hardware
fault is no good.

I have been getting accustomed to Sun and Dell systems crashing way
too often :-(.  One of the merits of the pSeries hardware is that it's
got the maturity of IBM's long term experience at building reliable
servers.  If the IBM hardware was a bit slower (unlikely, based on it
being way newer than the older Suns), but had suitable reliability,
that would seem a reasonable tradeoff to me.

I take the very same perspective on the discussions of "which
filesystem is best?"  Raw speed is NOT the only issue; it is
secondary, as far as I am concerned, to "Is It Reliable?"
--
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http://cbbrowne.com/info/lsf.html
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Cool, but are far too vulnerable to breakdowns."