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Oracle Internal Parameter set for Unix

原创 Linux操作系统 作者:yanggq 时间:2019-07-21 21:03:02 0 删除 编辑

in Linux /etc/system


Asked Tom,

a. db1 – concurrent users + processes = 410
b. db2 – concurrents users + processes = 50
c. db3 – concurrents users + processes = 50

The above three databases are going to be housed on one server.

What is the best way to calculate the kernel parameters based on the above information? Is there a formula for each of the kernel parameters? I see the below values in the preinstallation documentation but they do not specify the formula? Can you please help me with the formula?

SHMMAX 4294967295
SHMMIN 1
SHMMNI 100
SHMSEG 10
SEMMNS 200
SEMMNI 70
SEMMSL Equal to the value of the PROCESSES initialization parameter.

Thanks,
Sing and we said...
SHMMAX = The maximum size(in bytes) of a single shared memory segment.
SHMMIN = The minimum size(in bytes) of a single shared memory segment.

The above settings let the max be bigger then we will ever use and the min much smaller. They are sufficient for pretty much all systems.

SHMMNI = The number of shared memory identifiers.
SHMSEG = The maximum number of shared memory segments that can be attached by a process.

The above settings should also be sufficient.

SEMMNS = The number of semaphores in the system.
SEMMNI = The number of semaphore set identifiers in the system;
determines the number of semaphore sets that can be created at any one time.
SEMMSL = The maximum number of semaphores that can be in one semaphore set. It should be same size as maximum number of Oracle processes
(The PROCESSES parameter in the init.ora file).

SEMMSL
Set to 10 plus the largest initsid.ora PROCESSES parameter of an Oracle database on the system. The PROCESSES parameter can be found in each initsid.ora file, loc ORACLE_HOME/dbs directory. The default value of PROCESSES for the 8.1.5 prebuilt database is 50.

SEMMNS
Set to the sum of the PROCESSES parameter for each Oracle database the largest one, plus 2 times the largest PROCESSES value, plus 10 number of Oracle databases. For example, consider a system that has three Oracle instances with the PROCESSES parameter in their initsid.ora files set to the following values:
ORACLE_SID=A, PROCESSES=100
ORACLE_SID=B, PROCESSES=100
ORACLE_SID=C, PROCESSES=200
The value of SEMMNS is calculated as follows:
SEMMNS = ((A=100) + (B=100)) + ((C=200) * 2) +
((# of instances=3) * 10) = 630

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