SAP installer lying about kernel tuanbles

[Ralph Grothe]

Hi,

DBAs currently are trying to install yet another SAP monster.

Their installation routine aborts with these error messages:

ERROR 2004-03-24 16:53:03 INSTANCEPROFILE_IND_IND CheckProfile:0
While generating instance profile parameters are exceeding
system-imposed limit. Max. size of shared memory segments is 0.
Required size by SAP is 253132800. Please reconfigure the shared
memory segment size of your OS kernel.

ERROR 2004-03-24 16:53:03 INSTANCEPROFILE_IND_IND InstallationDo:0
Phase failed.

ERROR 2004-03-24 16:53:03 Main :0
Installation aborted.


The shared memory tunables were set according to SAP recommendations, and at least shmmax and shmseg are far from the above alleged naught.

# kmtune|grep shm
core_addshmem_read 0 Y 0
core_addshmem_write 0 Y 0
shmem 1 - 1
shmmax 17179869184 Y 17179869184
shmmni 256 - 256
shmseg 200 Y 200

[James A. Donovan · Accepted solution]

Total shot in the dark here.

Could your value of shmmax actually be too LARGE for the SAP installer program? Try setting shmmax to 1 GB temporarily and rerunning the install.

[Hein van den Heuvel]

You shmmax is too large.
Reduce to be below 4GB.
Maybe even less than 2GB.
You will NOT notice a performance for this reduction.

How mych physical memory do you have?
How much do you intend to give to SAP (extended memory)and/or ORACLE (sga).

Even if you wanted SAP (or ORACLE) to run with say 6GB shared memory, there is not going to be a difference between a single 6GB section and 3 times 3GB.

Cheers,
Hein.

[Ralph Grothe]

Hm, you both may be right.
But the paper with the SAP recommendations I got from the DBAs in order to build and boot an appropriate kernel prior to installation explicitly states
shmmax >= 17,179,869,184

The box has some 8 GB phys. memory installed

# echo "sc prod mem;info;wait;il"|cstm|grep Total\ Configured
Total Configured Memory : 8192 MB

The funny thing is that we have another box which even has less memory (i.e. 5 GB) but has a kernel running with exacvtly the same values for shared mem tunables seems to be reconciled.

Anyway, I will follow your suggestion and half the shmmax value to 0x200000000,
because currently this value is set (and thanks to 11i this is one of the few dynamical tunables)

# echo "obase=16;$(kmtune -q shmmax|awk '$1~/shmmax/{print$2}')"|bc
400000000

[Ralph Grothe]

Queer things are happening.
After having kmtune-d the shmmax to this value

# kmtune -q shmmax
Parameter Current Dyn Planned Module Version
===============================================================================
shmmax 200000000 Y 200000000

the SAP installer is suddenly calculating a non-zero but too small shared memory segment size.

ERROR 2004-03-25 09:37:26 INSTANCEPROFILE_IND_IND CheckProfile:0
While generating instance profile parameters are exceeding
system-imposed limit. Max. size of shared memory segments is
134217728. Required size by SAP is 253132800. Please reconfigure
the shared memory segment size of your OS kernel.


What's going on here?

[Ralph Grothe]

Actually, the SAP installer must have been written by some madmen.
As it seems, the shmmax hasn't been too large for the installer but rather too small.
After several fruitless attempts of dynamically decreasing shmmax in halving steps I gave it a shot in the opposite direction, and doubled shmmax.
It then stood at an incredible 0x800000000 (or some 34 GB dec).
And surprise, surprise, the installer didn't croak anymore.

[Jean-Luc Oudart]

Ralph,

I wonder I SAP (like some other suppliers) check that your swap area is x times your Physical memory, and then run some "logic" and check shmmax ,...
(how much swap area o this server compared to the other one ?)

~~~~~~~~~~~~~~~~~~~~
The box has some 8 GB phys. memory installed

# echo "sc prod mem;info;wait;il"|cstm|grep Total\ Configured
Total Configured Memory : 8192 MB

The funny thing is that we have another box which even has less memory (i.e. 5 GB) but has a kernel running with exacvtly the same values for shared mem tunables seems to be reconciled.
~~~~~~~~~~~~~~~~~~~~~~~~

Regards,
Jean-Luc

[Ralph Grothe]

Jean-Luc,

the SAP requirements are some 20 GB Swap.
Not to waste that much (mirrored) disk space the primary swap device was configured to be 10 GB wide.
This together with pseudo swap should satisfy later operational swap reservation requirements in my view.
Therefore, only for the purpose of SAP installation, I added the remaining 10 GB as least priority filesystem swap in the savecrash area (which isn't even mirrored).

# swapinfo -tam
Mb Mb Mb PCT START/ Mb
TYPE AVAIL USED FREE USED LIMIT RESERVE PRI NAME
dev 10000 0 10000 0% 0 - 1 /dev/vg00/lvol2
localfs 1808 0 1808 0% none 2000 9 /var/adm/crash/paging
reserve - 200 -200
memory 6331 553 5778 9%
total 18139 753 17386 4% - 2000 -

# du -skx /var/adm/crash/paging
10240136 /var/adm/crash/paging