Re: Solaris initdb fails: shmmax tweak alternative? - Mailing list pgsql-hackers

From Tom Lane
Subject Re: Solaris initdb fails: shmmax tweak alternative?
Date
Msg-id 29342.1081133095@sss.pgh.pa.us
Whole thread Raw
In response to Solaris initdb fails: shmmax tweak alternative?  ("Greg Sabino Mullane" <greg@turnstep.com>)
Responses Re: Solaris initdb fails: shmmax tweak alternative?  ("Greg Sabino Mullane" <greg@turnstep.com>)
List pgsql-hackers
"Greg Sabino Mullane" <greg@turnstep.com> writes:
> I am trying to get version 7.4.2 installed on a Solaris box, but
> initdb fails because of shmmax being set too low. It does this
> even though initdb drops shared buffers as low as it can go (50).
> Is there any other way of getting around this limitation?

IIRC you can put it as low as 16 without having to resort to changing
the backend C code (you'll need to drop max_connections to 8 at the
same time).  50 is just the lowest value initdb troubles to probe,
but you could hack the initdb script easily to try smaller values.

Whether you'll get decent performance or stability at such a tiny
setting is another question.

> I know that 50 is pretty low, but the recommended way (changing
> shmmax) involves rebooting a production machine and, while possible,
> is not preferred.

[ raises eyebrow... ] So you're installing a test database server on a
production machine?  That's not preferred admin practice anywhere that
I know of.  If it's really going to be a production server, I won't have
a lot of sympathy for the performance problems that you'll doubtless
have, small database or no.
        regards, tom lane


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