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The following kernel parameters need to be configured when installing the database:

Fs.aio-max-nr = 1048576fs.file-max = 6815744kernel.shmall = 2097152kernel.shmmax = 4294967295kernel.shmmni = 4096kernel.sem = 25032000100 128net.ipv4.ip_local_port_range = 900065500net.core.rmem_default = 262144net.core.rmem_max = 4194304net.core.wmem_default = 262144net.core.wmem_max = 1048576

Quote from: https://docs.oracle.com/cd/E11882_01/install.112/e47689/pre_install.htm#LADBI1187

Semaphores and shared memory are two distinct sets of operating system resources. Semaphores are the system resources used by Oracle for inter-process communication, which occupy relatively small memory space, while shared memory is used to contain SGA and can take up most of the physical memory.

Aio-max-nr: the maximum number of events that can be allowed in the context of all activity async Iamp O. The default value is 65536: the maximum number of file handles that the kernel can open; shmmax: specifies the maximum number of shared memory segments allowed by the kernel in bytes. The 64-bit default is 68719476736. The 32-bit default is 4294967295. Note: however, the kernel supports much more values than this value. In oracle, the minimum configuration is 536870912, the maximum 64-bit value is physical memory-1 byte, and the 32-bit maximum value is less than 4GB-1 bytes or 4294967295. It is recommended to set the physical memory size to 1 Universe 2 × shmall: specify the total amount of shared memory that can be used in the system at a time in bytes. The 64-bit default is 4294967296. The 32-bit default is 268435456. The minimum value recommended by oracle is 2097152. A value of less than 2097152 can be used when memory is small, and when memory is large (more than 8G), you need to plan by the following formula: formula 1:memtotal/pagesize. Formula 2: (SHMMAX/getpagesize () * (SHMMNI/16)). Shmmni: the maximum number of shared memory segments within the system. The default value in both 64-bit and 32-bit architecture machines is 4096sem: the semaphores acronym. There are four values corresponding to this. The recommended value for oracle is kernel.sem = 32000 100128, which corresponds to SEMMSL | maximum number of semaphores in a semphore set | 250 | defines the maximum number of semaphores for each Oracle database. | value range: 1-65536SEMMNS | maximum number of semphores in the system | 32000 | define the maximum semaphore on the system. | value range: 1-2147483647 SEMOPM | maximum number of operations per semop (P) call | 100 | define the maximum number of operands for each semop call. | | value range 100SEMMNI | maximum number of semaphore sets in system | 128 | define the maximum number of semaphore sets in the entire system | value range 1-32768 Rule: SEMMNI*SEMMSL > = the sum of process+10 of each instance in the SEMMNS,SEMMNS= system + 2*max (process) |

The corresponding relationship between operating system and kernel.sem parameters in sysctl

$ipcs-ls- Semaphore Limits-max number of arrays = 128 / / SEMMNImax semaphores per array = 250 / / SEMMSLmax semaphores system wide = 32000 / / SEMMNSmax ops per semop call = 100 / / SEMOPsemaphore max value = 32767

Issues related to semaphores:

Question 1:

SQL > startup nomountORA-27154: post/wait create failedORA-27300: OS system dependent operation:semget failed with status: 28ORA-27301: OS failure message: No space left on deviceORA-27302: failure occurred at: sskgpcreates [root@prodb linux] # ipcs-s-Semaphore Arrays-key semid owner perms nsems 0x00000000 0 root 600 1 0x00000000 65537 root 600 1 0x9a31ff94 1507331 oracle 640154 in this example, the SEMMNI value needs to be adjusted to 200 or more.

Question 2:

Getting ORA-600 [OSDEP_INTERNAL] errors while starting up the database:ORA-00600: internal error code, arguments: [OSDEP_INTERNAL], [] ORA-27302: failure occurred at: skgpwreset1ORA-27303: additional information: invalid shared ctxORA-27146: post/wait initialization failedORA-27300: OS system dependent operation:semget failed with status: 28ORA-27301: OS failure message: No space left on deviceORA-27302: failure occurred at: sskgpsemspersemmns value is too small Modified to: kernel.sem = 256 32768 100 228

Deletion of semaphore

Semaphore or shared memory errors mainly occur when the instance is started (especially in the 'startup nomount' phase). This is the only time Oracle tries to get the semaphore and shared memory of the instance. During normal database operations, errors related to semaphores or shared memory are rare. The most common occurrence of these errors is during the creation of a new database. However, sometimes the operating system may not be able to release the shared memory segment when the Oracle instance crashes. This limits the total amount of shared memory that the instance can use to start again. In this case, you need to delete these segments manually.

[oracle@prodb ~] $ORACLE_HOME/bin/sysresvIPC Resources for ORACLE_SID "PROD3": Shared Memory:ID KEY1966083 0x000000001998852 0x000000002031621 0x4db7973cSemaphores:ID KEY1507331 0x9a31ff94Oracle Instance alive for sid "PROD3" Linux:% ipcrm shm 2031621 1998852 1966083Other Unix:% ipcrm-m 12189717

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