started playing with jails

Bill Moran wmoran at
Wed Mar 21 21:56:51 UTC 2007

In response to Antony Mawer <fbsd-questions at>:

> On 22/03/2007 3:50 AM, Greg Barniskis wrote:
> > Bill Moran wrote:
> >> My experiments with Postgres in jail predate the existence of that 
> >> setting.
> >> When I was working with it, you had to frob a sysctl via /etc/sysctl.conf
> >>
> >> But even then, I couldn't seem to get it to work -- the Postgres in the
> >> jail would corrupt the shared memory of the postgres outside the jail.
> >> It was ugly.  Imagine big, wet tears rolling down my cheeks.
> >>
> >> I haven't had the need to try it in a while, so it might work OK now, I
> >> just don't know.
> >>
> > 
> > Ah, now that you mention it I do recall discussions of multiple 
> > instances peeing in each others pools so to speak. I also thought there 
> > was discussion of how to fix it, but have no idea where that went if 
> > anywhere...
> > 
> > A single instance inside a jail does work quite happily if the knob 
> > above is set.
>  From memory, I think the discussion went something like "Postgres uses 
> the TCP port number it binds to as its SYSV IPC ID... so if you want to 
> run multiple instances in jails/etc without conflict, run them on 
> different port numbers (and consequentially they will get separate SYSV 
> IPC IDs)".

That's how I remember it as well.  I don't remember being able to get
it working with a different port # either, but it's been a while -- back
when 7.4 was the latest.

Bill Moran

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