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From Eric Newton <eric.new...@gmail.com>
Subject Re: System swappiness setting warning - important enough to display when shell starts?
Date Fri, 08 Jun 2012 02:17:46 GMT
That's true, but this is not for performance.  If you run a large VM on
linux, with swappiness at 60, the OS will steal your pages, cause you to
swap, miss your deadlines, and crash your tserver.  But only after letting
you think everything is fine for an hour or so.

Another example: accumulo will now detect configurations where
cache+memory-map > max memory.  Before, it would work for a while, and then
... slow death by stop-the-world garbage collection.  Better to detect it
up-front an not have to sherlock it from log files.

-Eric

On Thu, Jun 7, 2012 at 9:31 PM, Jim Klucar <klucar@gmail.com> wrote:

> I think that could be a slippery slope. We can't possibly support all
> the Linux settings required for optimal performance on all
> distributions.
>
> Sent from my iPhone
>
> On Jun 7, 2012, at 7:36 PM, David Medinets <david.medinets@gmail.com>
> wrote:
>
> > I don't know the impact when this setting is too high. Apparently the
> > default in Ubuntu is 60. I only noticed the warning because I was
> > looking at log files randomly. I'm wondering if this check is
> > important enough to be done when the shell starts and to display the
> > error to the console at that time.
> >
> > This was the message:
> >
> > [server.Accumulo] WARN : System swappiness setting is greater than ten
> > (60) which can cause time-sensitive operations to be delayed.
> > Accumulo is time sensitive b
> > ecause it needs to maintain distributed lock agreement.
>

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