Re: Solaris 2.3 shared memory

dmargrav_at_stellar.comnet.com (David Margrave) writes:

>Can anyone offer some advice on how to select the values for the shared
>memory and semaphore parameters in the /etc/system file, for running Oracle?
>
>My system is running solaris 2.3, and has about 160 MB of memory and twice
>as much swap. Here is what I am using, partly from the oracle manuals and
>partly guessed:
>
>set shmsys:shminfo_shmmax=8388608
>set shmsys:shminfo_shmmni=400
>set shmsys:shminfo_shmseg=15
>set semsys:seminfo_semmns=100
>set semsys:seminfo_semmni=100

shminfo_shmmax is the largest shared memory segment allowed by Solaris, which you have set to 8M. The maximum number of segments in the above configuration are 15 OR the system can allocate upto 15 shared memory segments. The shared memory required by oracle DB is determined by the size of your SGA. Keeping shminfo_shmmax larger than your SGA may improve performance since the entire SGA will fit in one shared memory segment. shminfo_shmmax could be as large as the real memory since it is logical size of a segment (address range of a segment). Less segments, less overhead. if you are running 2.3, you should be running at a patch level 101318-39 or higher for 7.0 and 101318-54 or higher for 7.1.

seminfo_semmns really defines how many semaphores you have in the system. The processes parameter in initSID.ora file is Oracle's requirement for number of semaphores. The processes parameter limits number of connections to the database. Since each connection (user) needs one semaphore, you can calculate how many semaphores you need in the system. Keep it higher so it won't break each time you create a new instance.

>
>Now in comparison, I have an RDI Powerlite 85 Sparc compatible laptop with
>64 MB of memory and about 160 MB of swap space. How should I adjust the
>parameters for this one? What guidlines are used or is this something that
>just comes with being a Unix guru?
>
>Thanks,
>
>David Margrave
>dmargrav_at_utw.com
>

Thanks,
Sumant Chaudhari Received on Tue Jul 11 1995 - 00:00:00 CEST