Re: SHMMAX on Linux/ Oracle 8.0.5

Hi harinder,

  To understand your query, you need to be familiar with the way Unix/Linux operates. Actually, the UNIX memoery manager will keep SHMMAX amount of memory as shared memory. Thus, the value of SHMMAX denotes the maximum amount of shared memory that you can possible have and not what u allocate. Shared memory is allocated in segments which is donw by the OS only.

  Oracle mentions that the SGA MUST lie in shared memory, so your SHMMAX parameter must be greater than your SGA size, else your SGA cannot be created and Oracle won't start at all. The SHMMAX parameter has nothing to do with your database size or the number of rows in any table.

have a nice day,
Chetan Wagle
Senior Database Consultant
Cambridge Technology Partners,
Bangalore, India

Harinder wrote in message <7s848g$mp1$2_at_news.vsnl.net.in>...
>Friends,
>I have installed Oracle 8.0.5 on a RedHat 6.0 system with 512 Mb RAM and a
>2Gb swap space.
>It runs perfectly fine.
>
>SGA size as defined by me in init.ora is 6Mb. Which I think is more than
>enough for
>a database of 8 tables with not more than 500 rows in any of them.!
>
>What I would want to know is:
>Why does the documentation with Oracle and even Oracle support recommend a
>SHMMAX value of 4 gig???
>
>The default value in redhat 6.0 is 32 mb. And Oracle seems to be working
>fine on that. I wanted to know
>as to how does a value of SHMMAX = 4Gb work when the total memory on the
>system is 512 Mb + 2Gb (swap)
>??
>
>Is this not funny that Oracle still wants me to recompile the kernel and
set
>SHMMAX to 4 Gb.
>
>-Harinder
>
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Received on Tue Sep 21 1999 - 01:08:28 CDT