Re: Postgres stopped running (shmget failed)

On Tue, 25 Jan 2005 11:18:05 -0500, Tom Lane <tgl@sss.pgh.pa.us> wrote:
> Don Drake <dondrake@gmail.com> writes:
> > This morning I found the postgres not running and the following in my log file:
>
> > 2005-01-25 01:38:22 FATAL:  could not create shared memory segment:
> > Cannot allocate memory
> > DETAIL:  Failed system call was shmget(key=5432001, size=273383424, 03600).
> > HINT:  This error usually means that PostgreSQL's request for a shared
> > memory segment exceeded available memory or swap space. To reduce the
> > request size (currently 273383424 bytes), reduce PostgreSQL's
> > shared_buffers parameter (currently 32768) and/or its max_connections
> > parameter (currently 40).
>
> I have seen this happen when the old shmem segment didn't get released
> for some reason, and your kernel settings are such that it won't allow
> creation of two shmem segments of that size at once.  For robustness
> it's probably a good idea to make sure you *can* create two such
> segments at once, but for the moment getting rid of the old one with
> "ipcrm" should be enough to let you restart the postmaster.
>
>                         regards, tom lane
>

I was able to just restart it, after the server died and before I
restarted nothing showed up in the ipcs output.

On an unrelated note, the value 273MB seems relatively low to me.  The
DB uses over  27GB for data and indexes, I would think it needs more
shared memory.

Thanks.

-Don

--
Donald Drake
President
Drake Consulting
http://www.drakeconsult.com/
312-560-1574