Oracle Study case-install Oracle kernel parameter configuration

Oracle Study case-install Oracle kernel parameter configuration

In Linux, before installing Oracle, one of the key points in the system is to modify the kernel parameters, in addition to checking that the hardware and software of the operating systems meet the installation needs, most notably the memory-related parameter settings.

Case Analysis:

View the current Kernel parameter configuration for the system:

[[Email protected] ~]# sysctl -pnet.ipv4.ip_forward = 0net.ipv4.conf.default.rp_ filter = 1net.ipv4.conf.default.accept_source_route = 0kernel.sysrq =  0kernel.core_uses_pid = 1net.ipv4.tcp_syncookies = 1error:  " Net.bridge.bridge-nf-call-ip6tables " is an unknown keyerror: " Net.bridge.bridge-nf-call-iptables " is an unknown keyerror: " Net.bridge.bridge-nf-call-arptables " is an unknown keyfs.aio-max-nr =  1048576fs.file-max = 6815744kernel.shmall = 2097152kernel.shmmax =  536870912kernel.shmmni = 4096kernel.sem = 250 32000 100 128net.ipv4.ip_ local_port_range = 9000 65500net.core.rmem_default = 262144net.core.rmem_max =  4194304net.core.wmem_default = 262144net.core.wmem_max = 1048586

shmmax parameter:

linux process can allocate the maximum value of a separate shared memory segment. Generally set to half the total memory size. The setting for this value should be greater than the value of Sga_max_target or memory_max_target, so for systems that have an Oracle database installed, the value of Shmmax should be greater than one-second of the memory.
# grep memtotal/proc/meminfo
# Cat/proc/sys/kernel/shmmax
The above command is to check the size of system memory and the current Shmmax settings.
# echo 21474836480 >/proc/sys/kernel/shmmax
# sysctl-w kernel.shmmax=21474836480
# echo "kernel.shmmax= 21474836480 ">>/etc/sysctl.conf
This is a few ways to set the Shmmax parameter, which can be set to 20G in all three ways. This parameter can be modified without restarting the database. The method of using the second SYSCTL command is recommended by the individual. A third approach is required to perform a sysctl–t operation or reboot, but the third way is necessary to ensure that the setting value is still in effect after the next reboot. The first two approaches are similar to the alter system set scope = memory, whereas the third way is similar to the alter system set scope = SPFile.
Shmmni parameter:

Set the maximum number of shared memory segments at the system level. ORACLE10G recommended minimum value is 4096, can be appropriate than 4096 to increase some.
# Cat/proc/sys/kernel/shmmni
# echo 4096 >/proc/sys/kernel/shmmni
# sysctl-w kernel.shmmni=4096
# echo "kernel.shmmni=4096" >>/etc/sysctl.conf
Check and set method as above, this and Shmmax modification way no difference, not repeat.
shmall parameter:

Set the total number of shared memory pages. This value is too small to cause the database to start an error. Many people only focus on the Shmmax parameter when adjusting the kernel parameters of the system, ignoring the setting of the Shmall parameter. This value is recommended to be set to the physical memory size divided by the paging size.
# getconf Page_size
Gets the size of the paging through getconf, which is used to calculate the reasonable setting value for Shmall:
sql> select 32*1024*1024*1024/4096 from dual;
32*1024*1024*1024/4096
----------------------
8388608
for 32G of memory, 4K paging-size systems, the Shmall value should be set to 8388608.
# Cat/proc/sys/kernel/shmall
# echo 8388608 >/proc/sys/kernel/shmall
# sysctl-w kernel.shmall=8388608
# echo "kernel.shmall=8388608" >>/etc/sysctl.conf
Query and Setup method as above.
semaphore semaphores is a synchronization that is provided when the shared memory is accessed between processes or threads Counter.

Set the maximum number of semaphores in each semaphore group, the recommended minimum value is 250. For systems with a large number of concurrent connections, it is recommended that this value be set to the processes initialization parameter plus 10.
Semmni Parameters:

Sets the maximum number of semaphore groups in the system. The recommended value for oracle10g and 11g is 142.
Semmns Parameters:

Set the maximum number of semaphores in the system. The operating system does not exceed least (Semmns,semmsl*semmni) when assigning semaphores. In fact, if the value of Semmns exceeds Semmsl*semmni is illegal, the recommended Semmns value is set to Semmsl*semmni. Oracle recommends that the setting of semmns is not less than 32000, if the processes parameter of the database is set to 600, the Semmns setting should be:
Sql> Select (600+10) *142 from dual;
(600+10) *142
------------
86620
semopm parameter:

Sets the maximum number of semaphore operations that can be performed at the same time per system call. Since a signal light group has a maximum of SEMMSL semaphores, it is recommended that the SEMOPM be set to the value of SEMMSL. Oracle verifies that the 10.2 and 11.1 semopm are configured with 100.
The following command allows you to check the semaphore related configuration:
# Cat/proc/sys/kernel/sem
250 32000 100 128
The corresponding 4 values are SEMMSL, Semmns, SEMOPM, and Semmni, respectively, from left to right. Modify the method to:
# echo 610 86620 142 >/proc/sys/kernel/sem
# sysctl-w kernel.sem= "610 86620 100 142"
# echo "kernel.sem=610 86620 142" >>/etc/sysctl.conf

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Oracle Study case-install Oracle kernel parameter configuration