Re: sga_max_size problem (Warning in alert log)

On May 14, 4:59 pm, christianeriks..._at_vfemail.net wrote:
> Hi!
>
> I would be most grateful if anyone could explain in detail what's
> going on here. We have a warning message in the alert log saying:
>
> WARNING: EINVAL creating segment of size 0x0000000101400000
> fix shm parameters in /etc/system or equivalent
>
> and this hexadecimal value I find to be 4315938816 in decimal. Now the
> question is why oracle tries to allocate this value because we have
> set a smaller value in the spfile:
>
> oracle_at_S0242169# grep sga_max_size /SSW/oracle/product/9.2.0.6.0/dbs/
> spfiledw
> *.sga_max_size=4294967296
>
> which is the same value as in /etc/system
>
> oracle_at_S0242169# grep shmmax /etc/system
> set shmsys:shminfo_shmmax=4294967296
>
> (and the system is indeed started with this value:
>
> oracle_at_S0242169# sysdef | grep -i shmmax
> 4294967296 max shared memory segment size (SHMMAX))
>
> Despite the above the instance ends up with a larger memory allocation
> than sga_max_size and shmmax:
>
> oracle_at_S0242169# echo "show parameter sga_max_size" | sqlplus -s '/ as
> sysdba'
>
> NAME TYPE
> VALUE
> ------------------------------------ -----------
> ----------------------------
> sga_max_size big integer 4296515696
>
> Why is that?
>
> Can it have something to do with oracle rounding up it's memory
> allocation to "a page boundary" as stated in the below qoute:
>
> >Fromhttp://www.dba-oracle.com/t_shared_memory_ram_unix_errors.htm
>
> 3) The size of the shared memory segment requested is invalid. In
> this
> case, EINVAL is returned by the system. This should be very rare
> - however,
> it is possible. This can occur if SHMMAX is not a mulitple of
> page
> size and Oracle is trying a multi-segment model. Remember that
> Oracle
> rounds its calculation of SHMMAX to a page boundary, so it may
> have
> rounded it up past the real SHMMAX! (Whether this is a bug is
> debatable).
>
> OS: Solaris 9 9/04 s9s_u7wos_09 SPARC
> Oracle server: Oracle9i Enterprise Edition Release 9.2.0.6.0 - 64bit
> Production
>
> Regards Christian Eriksson

Your SHMMAX value is set to 4 gig, and I doubt very seriously you'll have page boundary issues with that allocation. I'm expecting this is possibly a bug, fixed in a subsequent patch. You need to patch this installation to 9.2.0.8, test again, and if the problem persists contact Oracle Support.

David Fitzjarrell Received on Tue May 15 2007 - 08:06:38 CDT