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Oracle needs to pay attention to some details when using Linux large pages.

1. Need to use SGA memory management, or return to 9i mode, each pool manual management

two。 Large pages set by the system cannot be used by oracle when managing memory in memory_target mode

Whether 3.oracle makes use of large pages can be viewed through the / proc/meminfo file, and will be recorded when the alert log starts.

4. It will improve the performance of OS system, reduce the size of huge table page table, and reduce system overhead.

5. Some oracle under linux respond slowly in busy systems because there is no reasonable use of large pages and can cooperate with OSW data analysis.

Linux sets large pages as follows:

1. Close all oracle instances

It is recommended that you close the database instance when modifying large pages, or operate separately between nodes.

Srvctl stop database-d orcl

two。 Use the root user to modify the / etc/security/limits.conf file on both nodes, and finally add two lines:

Oracle hard memlock unlimited

Oracle soft memlock unlimited

3. Allocate hugepages memory and use the root user two nodes to modify / etc/sysctl.conf to add the following:

The unit of large page is generally 2m, and this parameter represents the quantity. This example is 256g.

Vm.nr_hugepages = 131074

Note: the number of large pages is usually set using the following formula, divided by 2 means that each large page under Hugepage management is 2m.

Select ceil (SGA_MAX_SIZE (G) * 1024lap2) + 2 from dual

4. Use root users to perform sysctl-p to make it more effective and monitor their space allocation.

Sysctl-p

Grep Huge / proc/meminfo

5. Start all Oracle instance in the RAC cluster

Srvctl start database-d orcl

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