Out of memory

[Frank de Vries]

Memory

With 3Giga you should easily be
able to configure 2 Oracle instances.
Enough volume in total.

A very simple rough rule of thumb
to start with - and then after you
can always tune a bit.
Is the rule of a third.

- A third for OS
- A third for PGA and application
- A third for SGA

So if you have 2 Oracle instances,
you could use 1Giga between them.

Please do not oversize on the block buffers.
At a certain point giving more block buffers does not speed up things but just wastes memory. It should not be a bottleneck that is
all. The rest of memory should go to library cache, shared pool and java pool.

Also ensure that the sga memory fits as one
contiguous area into the unix memory :
check with ipcs -m.
If not indeed tune the unix kernel accordingly.

Last but not least ensure the Oracle instances can allocate enough metaphores
for keeping track of its internals.
check with ipcs -s and the kernel

[orapic@orasrv2:]/stand/build<>>> grep -i SEMM tune.h
#define SEMMAP (SEMMNI+2)
#define SEMMNI 520
#define SEMMNS 1024
#define SEMMNU 512
#define SEMMSL_OVERRIDE 2048

If you still have problems let us know
what the error is.

regards

[mehul_3]

I have reduced one of SGA size by 700MB, still the problem persists.

Pl, help me...

Rgds,
Mehul

[Frank de Vries]

Okay,
You have run into a specific memory problem
that is very specific.
There is a constraint on the OS level
that we need to tune.

Three obvious supspects:

1) swap - can you give the output of swapinfo
and swapinfo -t
2) The kernel parameters - also post output
of sysdef | grep max , sysdef | grep sh and
sysdef | grep sem
3) Defracted Unix memory - post output of ipcs -a

Regards,
Frank

[Frank de Vries · Accepted solution]

By the way I found this on metalink,
and it does not look very good.
May not be your fault at all.

Solution Description
--------------------

Check hardware memory and reboot the box. After restart the server,
all databases can be startup.


Explanation
-----------

HP-UX error 12: not enough space usually means there is not enough
real memory or swap space. In this case, it seems hardware has some
problem freeing the memory. Apparently reboot the box fix the problem


Personally I can't believe just a reboot
would solve it, but in essence it could
be that we have to clear the memory manually
with the ipcrm -m command.

Let me know how ou get on.

Regards,

[Frank de Vries]

I found another note that could be interesting:

Issue command ulimit -a
You would see
data :
stack :
memory :
vmemory :
From your sys admin, increase these values to
a reasonable ones.
Should solve your problem.

Hope this is the winning ticket :°)

[mehul_3]

Dear all,
Thanks to all who gave a detailed explanation and updating my knowledge.
Problem has been solved after rebooting a server.

Thanks once again.

Rgds,
Mehul

[Bill Hassell]

Just a note about the errno 12 error message. While it is true that the error indicates not ehough memory, this isn't simply all memory is used, it really means that a request was refused by the OS. The reason can be due to not enough virtual memory (which is RAM plus swap space), but it can also be due to kernel fences or limits to prevent runaway programs. It can also be due (as mentioned before) to memory fragmentation within a limited map. IF it happens again, you can easily verify that it is due to lack of virtual memory be adding a large amount of filesystem swap space while the box is running. Use swapon to do this. Add perhaps 2-3 Gb space and see if the problem goes away. And defeinitely get the maxdsiz value fixed as the strange number from kmtune may be part of the problem too.