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Editor to share with you how to set the / etc/sysctl.conf kernel parameters when installing Oracle under Linux. I hope you will get something after reading this article. Let's discuss it together.

You need to adjust the kernel parameters of linux when installing Oracle, but what do these parameters mean? let's analyze them in detail.

The minimum value given in the Linux installation documentation:

Fs.aio-max-nr = 1048576

Fs.file-max = 6815744

Kernel.shmall = 2097152

Kernel.shmmax = 4294967295

Kernel.shmmni = 4096

Kernel.sem = 250 32000 100 128

Net.ipv4.ip_local_port_range = 9000 65500

Net.core.rmem_default = 262144

Net.core.rmem_max = 4194304

Net.core.wmem_default = 262144

Net.core.wmem_max = 1048586

Detailed description of each parameter:

Kernel.shmmax:

Is one of the most important core parameters that defines the maximum value of a single shared memory segment. The setting should be large enough to accommodate the entire SGA under one shared memory segment, and a low setting may result in the need to create multiple shared memory segments, which may lead to system performance degradation. The main reason for the system decline is that when the instance is started and the ServerProcess is created, multiple small shared memory segments may lead to a slight degradation of system performance at that time (multiple virtual address fields need to be created at startup, and there will be some impact when the process is created to let the process "identify" multiple segments), but it will not be affected at other times.

Official recommended values:

32-bit linux system: the maximum preferred value is 4GB (4294967296bytes)-1byte, which is 4294967295. The recommended value is more than half of the memory, so if 32 is the system, the value is generally 4294967295. 32-bit systems have limits on the size of the SGA, so the SGA can certainly be included in a single shared memory segment.

64-bit linux system: the maximum preferred value is physical memory value-1byte, and the recommended value is more than half of physical memory. Generally, the value is greater than SGA_MAX_SIZE, and you can take physical memory-1byte. For example, if it is 12GB physical memory, the preferred 12884901887 memory will definitely be included in a single shared memory segment.

Kernel.shmall:

This parameter controls the total number of pages of shared memory that can be used. The page size of Linux shared memory is 4KB, and the size of shared memory segments is an integral multiple of the size of shared memory pages. The maximum size of a shared memory segment is 16G, so the number of pages of shared memory needs to be 16GB/4KB=16777216KB / 4KB=4194304 (pages), that is, 16GB physical memory under 64Bit system. Set kernel.shmall = 4194304 to meet the requirement (almost double the original setting of 2097152). At this time, the shmmax parameter can be adjusted to 16G, and the SGA_MAX_SIZE and SGA_TARGET can be changed to 12G (the maximum size of SGA you want to set, of course, can also be 2G~14G, etc., and coordinate the use of PGA parameters and other memory such as OS. Do not set too full, for example, 16G).

Kernel.shmmni:

This parameter is the maximum number of shared memory segments. The default value of shmmni is 4096, which is generally sufficient.

Fs.file-max:

This parameter determines the maximum number of file handles allowed in the system, and the file handle setting represents the number of files that can be opened in the linux system.

Fs.aio-max-nr:

This parameter limits the concurrency of outstanding requests and should be set to avoid the failure of the Istroke O subsystem.

The recommended value is: 1048576, in fact, it is equal to 1024K 1024K.

Kernel.sem:

Take kernel.sem = 250 32000 100128 as an example:

250 is the value of the parameter semmsl, indicating the maximum number of semaphores that can be contained in a semaphore set.

32000 is the value of the parameter semmns, indicating the maximum number of semaphores allowed in the system.

100 is the value of the parameter semopm, which represents the number of operations that a single semopm () call can perform on a semaphore set.

The value of the parameter semmni represents the total set of system semaphores.

Net.ipv4.ip_local_port_range:

Represents the range of IPv4 ports that the application can use.

Net.core.rmem_default:

The default value that represents the size of the socket receive buffer.

Net.core.rmem_max:

Represents the maximum size of the socket receive buffer.

Net.core.wmem_default:

The default value that represents the size of the socket send buffer.

Net.core.wmem_max:

Represents the maximum size of the socket send buffer.

After reading this article, I believe you have some understanding of "how to set the kernel parameters of Oracle / etc/sysctl.conf when installing etc/sysctl.conf under Linux". If you want to know more about it, you are welcome to follow the industry information channel. Thank you for reading!

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