Thread: Setting shmmax in /etc/rc on Mac OS X to install Postgres

Would you please take a look at my problem thoroughly explained in this post on the Macrumors forum?  Any ideas on how to deal with this lack of memory problem?

I posted messages to numerous forums, to Mac and Postres support.  BTW I've been working on this problem, off and on, for 3 months now.

Any advice appreciated.

Thank you, Doug

The URL.

Doug Graham wrote:
> The URL. <http://forums.macrumors.com/showthread.php?p=8006958#post8006958>
>
> On Fri, Jul 3, 2009 at 7:47 AM, Doug Graham <duggram@gmail.com> wrote:
>
>> Would you please take a look at my problem thoroughly explained in this
>> post on the Macrumors forum?  Any ideas on how to deal with this lack of
>> memory problem?
>>
>> I posted messages to numerous forums, to Mac and Postres support.  BTW I've
>> been working on this problem, off and on, for 3 months now.
>>
>> Any advice appreciated.

I run 10.4.7 with 2GB RAM and use the following in /etc/sysctl.conf -

kern.sysv.shmmax=536870912
kern.sysv.shmall=131072
kern.sysv.shmmin=1
kern.sysv.shmmni=32
kern.sysv.shmseg=8

which is half a GB for shared memory.

In an earlier discussion it was mentioned that shmall * 4096 should be
greater or equal to shmmax - your shmmax is 4 times that.
shmmax should also be a multiple of 4096.

Also of note - you are setting the shmmax to 4GB which is all of your
ram to shared memory. A bit extreme even if it was a postgres only
dedicated server.

I'd start with setting shmmax to 1610612736 and working from there,
1.5GB  should be plenty to get started. Check that this setting sticks
with sysctl -a and then try postgrsql again.



--

Shane Ambler
pgSQL (at) Sheeky (dot) Biz

Shane Ambler <pgsql@Sheeky.Biz> writes:
> Also of note - you are setting the shmmax to 4GB which is all of your
> ram to shared memory. A bit extreme even if it was a postgres only
> dedicated server.

I have some recollection that OSX treats that as a 32bit number, which
means you *can't* set it >= 4GB.  Try 1GB or 2GB just to get it working.

            regards, tom lane

Shane and Tom, you guys nailed it.  Although I did have another problem.

I went with Shane's 1610612736 recommendation.  However, I suspected all was not well with my file.  I had saved it with Edit.  Found a vi guide, opened it with vi, cleaned out all the extra header garbage, chaned shhmax and save it.  Shut the mac down and restarted.  Postres started right up.

Now I have also uncovered another problem, how do you get rid of a sysctl.conf.swp file?  Couldn't get that done in vi.  But I can even see reference to it outside of vi.  If you don't have time to tell me I'll research deleting a swp file when I get done setting up my postgres.

Thank you all,
Doug

Doug Graham wrote:
> Shane and Tom, you guys nailed it.  Although I did have another problem.
>
> I went with Shane's 1610612736 recommendation.  However, I suspected all was
> not well with my file.  I had saved it with Edit.  Found a vi guide, opened
> it with vi, cleaned out all the extra header garbage, chaned shhmax and save
> it.  Shut the mac down and restarted.  Postres started right up.

Didn't think of non-plain text.. If you do use TextEdit again in the
Format menu select Make Plain Text. This is only an issue when you
create a new file - if you open an existing one it will retain the
format previously saved.

> Now I have also uncovered another problem, how do you get rid of a
> sysctl.conf.swp file?  Couldn't get that done in vi.  But I can even see
> reference to it outside of vi.  If you don't have time to tell me I'll
> research deleting a swp file when I get done setting up my postgres.

Not certain but I believe that is the vi temporary file. Maybe the rtf
codes messed it's cleanup. Or it had not exited cleanly. If your sure
your not editing the file then delete it.




--

Shane Ambler
pgSQL (at) Sheeky (dot) Biz

Tom Lane wrote:
> Shane Ambler <pgsql@Sheeky.Biz> writes:
>> Also of note - you are setting the shmmax to 4GB which is all of your
>> ram to shared memory. A bit extreme even if it was a postgres only
>> dedicated server.
>
> I have some recollection that OSX treats that as a 32bit number, which
> means you *can't* set it >= 4GB.  Try 1GB or 2GB just to get it working.
>
>             regards, tom lane
>

Could be - not a fully 64 bit clean kernel yet?
Maybe that will change with 10.6 - suppose to be a full 64 bit system,
right?

Although does it allow you to allocate 100% or more of physical ram to
shared mem?



--

Shane Ambler
pgSQL (at) Sheeky (dot) Biz