Installation guide

accordingly.
As shown in the The SEMMSL Parameter section above, the SEMMSL setting should be 10 plus the largest
PROCESSES parameter of any Oracle database on the system. So if you have one database instance running on
a system where PROCESSES is set to 5000, then SEMMSL should be set to 5010.
As shown in the The SEMMNS Parameter section above, the maximum number of semaphores that can be allo-
cated on a Linux system will be the lesser of: SEMMNS or (SEMMSL * SEMMNI). Since SEMMNI should be
set to 142, we need to increase SEMMNS to 711420 (5010*142).
As shown in the The SEMOPM Parameter section above, a semaphore set can have the maximum number of
SEMMSL semaphores per semaphore set and it is recommended to set SEMOPM equal to SEMMSL. Since
SEMMSL is set to 5010 the SEMOPM parameter should be set to 5010 as well.
Hence, if the ora.init parameter PROCESSES is set to 5000, then the semaphore settings should be as follows:
# sysctl -w kernel.sem="5010 711420 5010 142"
Setting File Handles
The maximum number of file handles specifies the maximum number of open files on a Linux system. Oracle
recommends that the file handles for the entire system is set to at least 65536.
To determine the maximum number of file handles for the entire system, run:
# cat /proc/sys/fs/file-max
49254
To determine the current usage of file handles, run:
# cat /proc/sys/fs/file-nr
5056 0 49254
The file-nr file displays three parameters:
– Total allocated file handles
– Currently number of unused file handles (2.6 kernel)
– Maximum file handles that can be allocated (see also /proc/sys/fs/file-max)
The kernel dynamically allocates file handles whenever a file handle is requested by an application but the ker-
nel does not free these file handles when they are released by the application. The kernel recycles these file han-
dles instead. This means that over time the total number of allocated file handles will increase even though the
number of currently used file handles may be low.
Note that using ASMLib driver decreases the total number of open files required for Oracle processes because
they do not have to open files or block devices directly.
The maximum number of file handles can be changed in the proc file system without reboot:
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