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This article mainly explains "how to maintain ORACLE semaphores and shared memory in various operating systems". The explanation in this article is simple and clear, easy to learn and understand. Please follow Xiaobian's train of thought to study and learn "how to maintain ORACLE semaphores and shared memory in various operating systems".

1.LIUNX

Cat / etc/sysctl.conf

Shared memory:

Kernel.shmall = 2097152 # the total amount of shared memory available, in pages. Value: recommended greater than shmmax/page_size (getconf PAGE_SIZE is generally 4096)

Kernel.shmmax = 2147483648 # maximum size of a single shared memory segment. Value: recommended greater than sag_max_size

Kernel.shmmni = 4096 # the maximum number of shared memory segments for the entire system. Value: default value

Semaphore:

Kernel.sem = 5010 641280 5010 128 # SEMMSL, SEMMNS, SEMOPM, SEMMNI

The maximum number of signal objects per signal object set; the maximum number of signal objects in the system; the maximum number of operands supported by each signal object; the maximum number of signal object sets in the system.

SEMMSL

Setting: minimum 250; for systems with large processes parameter setting, it is recommended to set it to processes+10

SEMMNS

Setting: at least 32000 position SEMMSL * SEMMNI

SEMOPM

Setting: at least 100; or equal to SEMMSL

SEMMNI

Meaning: the maximum number of semaphores set in linux system

Setting: at least 128

2.HPUX

Semaphore:

Kctune-h-B semmni= "4096" system-wide maximum semaphore Default: nproc (maximum number of system-wide processes)

Kctune-h-B semmns= "16384" the maximum semaphore that users can access is Default: semmni*2

Kctune-h-B semmnu= "4092" maximum number per semaphore Maximum: nproc-4

The maximum number of signal values allowed by kctune-h-B semvmx= "32767" Maximum: 65535

Shared memory:

Kctune-h-B shmmax= "34359738368" maximum shared memory segment size

Kctune-h-B shmem=1 starts / closes shared memory 1 (on)

The largest segment on the kctune-h-B shmmni= "4096" system

Kctune-h-B shmseg= "512" the maximum segment of each process Maximum: shmmni

3.AIX

AIX generally does not need to be adjusted manually, but the system is dynamic. If you report a shortage of shared memory or semaphores after running, you can increase the maximum number of processes allowed by a single user of maxuproc (with the command smitty system or chdev).

$su-root

# chdev-l sys0-a maxuproc=1000

4.Solaris

Modify Solaris 9 li / etc/system, and the reference value is as follows:

Semaphore:

Set semsys:seminfo_semmni=20000 specifies the maximum number of signal identifiers

Set semsys:seminfo_semmsl=29000 specifies the maximum number of System V signals per signal identifier

The maximum number of System V signals on the set semsys:seminfo_semmns=30000 system.

Set semsys:seminfo_semopm=31000 specifies the maximum number of System V signal operands for each semop call.

The total number of undo structures supported by the set semsys:seminfo_semmnu=32000 System V signaling system.

The maximum number of System V signal undo structures that set semsys:seminfo_semume=10 can use by any process

The maximum signal value that can be set by set semsys:seminfo_semvmx=32767

Shared memory:

The system-wide limit set by shmsys:shminfo_shmmni on the number of shared memory segments that can be created.

The maximum size of the System V shared memory segment that shmsys:shminfo_shmmax can create.

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Semaphore and shared memory management

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1.ORACLE provides sysresv tools to manage shared memory and semaphores

$sysresv-l "ORCL" to view the semaphore and shared memory corresponding to the instance

IPC Resources for ORACLE_SID "ORCL":

Shared Memory:

ID KEY

65537 0x3b751258

Semaphores:

ID KEY

98304 0xe21c75d0

Oracle Instance alive for sid "ORCL"

The sysresv-f parameter can remove the shared segment (only if the instance does not exist, and the operating system shared segment does not release the condition)

$export ORACLE_SID=orcl

$sysresv-f orcl

two。 The operating system level can be managed by ipcs/ipcrm (can be determined in combination with sysresv in multiple instances)

Ipcs-an or ipcs displays the usage of shared memory segments, semaphore sets, and message queues in the current system

Ipcs-m shows the usage of shared memory segments

Ipcs-s shows the usage of semaphore sets

Ipcs-Q shows the usage of message queues

The commands to clean up related shared memory, semaphores, queues and other shared information are as follows:

Ipcrm-s semid deletes the corresponding semaphore set

Ipcrm-m shmid deletes the corresponding shared memory segment

Ipcrm-Q msqid deletes the corresponding message queue

3. There are often some problems caused by the lack of clean cleaning of shared memory, semaphores, queues and other shared information.

For example:

SQL > startup

ORA-27154: post/wait create failed

ORA-27300: OS system dependent operation:semget failed with status: 28

ORA-27301: OS failure message: No space left on device

ORA-27302: failure occurred at: sskgpcreates

At this time, you may need to clean up the relevant semaphores (you can also increase the semaphore value).

Thank you for your reading, the above is the content of "how to maintain ORACLE semaphores and shared memory in various operating systems". After the study of this article, I believe you have a deeper understanding of how to maintain ORACLE semaphores and shared memory in various operating systems. Here is, the editor will push for you more related knowledge points of the article, welcome to follow!

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