Out of memory

[mehul_3]

Hi there!
Operating System HP-UX11i.
Physical RAM 3GB.
Database Oracle9.2.0.1.0
Two instanaces are running having SGA memory 1425MB and 290MB respectively.

Out of memory error is getting while application runs on frequently basis.
Attached screen shot is for referance.

Waiting for reply.

Rgds,
Mehul

[Joseph Loo]

hi,

any change of reducing the SGA with 1425MB or getting extra memory as 3GB is not exactly a lot? also, r the kernel parameter configure to accommodate 9.2.0.1?

u also sure have lots of unassigned points:

http://forums1.itrc.hp.com/service/forums/pageList.do?userId=CA1190244&listType=unassigned&forumId=1

regards.

[RAC_1]

Reduce the SGA on one of the instances or increase the shmmax a bit.

Also how is swap performing
swapinfo -mat
Also how cache has been set?

[Jean-Luc Oudart]

Hi

It seems yuo're running out of memory.
RAM 3GB
SGA 1715MB
Then yuo need memory for your PGA (oracle processes). When you have too many of them you run out of mempory !
What is the swap area
please post
dbc_min_pct
dbc_max_pct
swapinfo -tam

You will probably have to review SGA size and other oracle parameters unless you can increase the total RAM

Regards
Jean-Luc

[mehul_3]

I checked a swapinfo but I confused how much swap memory is assigned and used from the following output
# swapinfo -mat
Mb Mb Mb PCT START/ Mb
TYPE AVAIL USED FREE USED LIMIT RESERVE PRI NAME
dev 6144 2467 3677 40% 0 - 1 /dev/vg00/lvol2
reserve - 3673 -3673
memory 2315 996 1319 43%
total 8459 7136 1323 84% - 0 -

[RAC_1]

do not llok at swapinfo. you have set kernel tuanable swapmem_on to 1. this is pseudo swap and when set kernel calculates swap space as ->swap space configured + 75% of RAM.

you will have to decrease one of SGA or increase shmmax a bit. In any case, you shuold be adding memeory 3GB is not much of it for oracle.

[Jean-Luc Oudart]

From swapinfo -tam
your are using real swap area, therefore you will get poor performance.
Too big a SGA (!) is not any help if you are swapping out

you should run perfstat report to see which arra can be resized (downward) until you get more RAM (you really need more !)

Regards
Jean-Luc

[Yogeeraj_1]

hi,

you should review your init.ora initialisation parameters. As mentioned about, the statspack report can help you in determining which instance requires more memory than the other.

hope this helps too!
kind regards
yogeeraj

[Bill Hassell]

If the Oracle code is only 32bit (not 64bit), then it ALWAYS be difficult to allocate that much SGA. The reason is that a 32bit application is limited to about 1750 megs for shared memory, and the map that allocates this space is shared with all other 32 bit applications. Therefore, it will become fragmented as you stop and restart various programs. 3Gb is way too small to provide reasonable performance with these SGA settings. But increasing RAM to 6-8Gb won't help with the shared memory fragmentation, it will stop the paging out to swap.

Use shminfo program to show you how the shared memory map has become fragmented:

ftp://contrib:9unsupp8@hprc.external.hp.com/sysadmin/programs/shminfo/

There are several ways to fix the out-of-memory errors:

1. Reboot - the memory map will be rebuilt and everything will fit (not a good choice for a production machine).

2. Reduce the SGA sizes - Oracle will slow down as more activity is shifted from RAM to disk.

3. Upgrade Oracle and any middleware to 64bit execytables - now shared memory has a massively large map and fragmentation is longer an issue.

4. Implement memory windows - this involves creating a separate window for each instance of Oracle (and any middleware that uses Oracle SGA). This eliminates fragmentation because SGA is in a private memory space. This will not improve performance, it will just prevent the out of memory errors. You still need to double RAM for best performance.

[Jean-Luc Oudart]

Bill

Oracle9i is 64bits

Regards
Jean-Luc