launchpad-dev team mailing list archive

[Guilherme Salgado <salgado@xxxxxxxxxxxxx>]

On Thu, 2010-12-02 at 15:41 +0700, Stuart Bishop wrote:
> On Mon, Nov 29, 2010 at 9:57 PM, Guilherme Salgado
> <salgado@xxxxxxxxxxxxx> wrote:
> > Hi there,
> >
> > Since the last kernel upgrade (yesterday, IIRC) I can no longer start
> > postgres up. I get the following error, and /proc/sys/kernel/shmmax is
> > indeed smaller than what postgres is requesting. After changing that
> > manually I was able to start postgres again.
> >
> > Has anybody seen that?  Should we report it as a bug against Ubuntu or
> > should we just lower the config variables that influence the size that
> > postgres passes on to shmget()?
> 
> I haven't seen on my local system. It is something we always have to
> change on production when we increase how much RAM PG should use.
> 
> If default PostgreSQL doesn't start up under default Ubuntu, that is a
> bug on the Ubuntu PostgreSQL package.

Right, but I couldn't tell for sure whether or not it fails to start on
a fresh installation as launchpad-database-setup changes the postgres
config.

It turns out that I had shared_buffers=32MB and max_connections=100 but
the failure tells me max_connections was at 103. Playing with those
variables (which are not changed by launchpad-database-setup), I was
able to make it start, but I wanted to know if it'd fail on a fresh
cluster as well, so I created one.

The new cluster came with 24MB for shared_buffers and 100
max_connections, so it started just fine.  But that left me wondering
where the 32MB I had came from (I don't remember changing that).  Maybe
from the previous version of postgres I used when creating the cluster?

Anyway, I guess I'll just change my shared_buffers to 24MB and get on
with life, but for the curious, the highest
shared_buffers/max_connections I can use seem to be 28MB/99 (on x86_64),
but William reports that he has 28MB/100 (with same shmmax) and it works
just fine (he's on i386, though).

-- 
Guilherme Salgado <https://launchpad.net/~salgado>

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