[GRLUG] NOT LINUX - hybrid drives

[Bob Kline]

On Mon, Nov 12, 2012 at 8:08 AM, Adam Tauno Williams <awilliam at whitemice.org
> wrote:

> On Sat, 2012-11-10 at 11:18 -0500, Bob Kline wrote:
> > On Sat, Nov 10, 2012 at 11:03 AM, Adam Tauno Williams
> > <awilliam at whitemice.org> wrote:
> > Bob Kline <bob.kline at gmail.com> wrote:
> > >
> http://www.amazon.com/gp/product/ref=pe_172730_26630760_pe_b2/?ASIN=B003NSBF32mainson spinning rust in the SSD case).
> > >Conceptually, the "sticky bit" in file
> > >permissions was intended for just that
> > >purpose,
> > I think the sticky bit was more about trying to control caching.
> > Do tell:
> > **
> > The sticky bit was introduced in the Fifth Edition of Unix for use
> > with pure executable files. When set, it instructed the operating
> > **
> > From http://en.wikipedia.org/wiki/Sticky_bit
> > The sticky bit might have evolved
> > into something more, but the concept
> > dates to the days when memory and
> > hard drive space was very limited.
>
> The UNIX sticky bit is an entirely historic footnote.  In ~25 years I've
> never worked on a system that implemented 'orthodox' stick-bit behavior
> - or at least where using it was ever advised.  [mostly because it is
> just a dumb idea]
>
> If we want to grasp at vague equivalencies I'd consider LD_PRELOAD to
> better resemble pre-load-the-good-stuff than the stick bit does.  But
> neither of these are really equivalent to storage tiering since the
> entire point of such tiering is that it is dynamic;  rather than the
> sys-admin [or worse, the developer] trying to guess [and inevitably
> being wrong] what data is upper-tier worthy.
>
>
Wouldn't it be simpler to just say
that things like the sticky bit are at
odds with the system scheduler?
Which in turn are said to be
notoriously hard to get right.

Apparently one can even suggest
today that a process be associated
with a specific CPU in a multi core
system, it won't necessarily happen,
for the same reason.

As for dumb idea, perhaps to the
extent that Ritchie and Thompson
were dumb, but saying that would
take a fair bit of hubris.  Ritchie
pointed out that the sticky bit was
one of the few Unix concepts that
was patentable.  i.e., many of the
basic ideas in CS go back 60 years,
even while the state of hardware
development kept them from being
practical until a lot later. And some
ideas simple don't pan out, or get
replaced by something better as
understanding improves. I doubt
that many things get cut from whole
cloth the first time.

That the sticky bit has few real
uses today is probably true.

   -- Bob
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