A tragedy caused by the Hugepages ORACLE session surge was not turned on

The fault simply describes: The Linux system does not open hugepages, the host memory will be nearly 300g,swap 32G. ORACLE's sga_max_size settings are nearly 500 of the host's internal memory, which is approximately 60% of the hosts, and the database session is normally about almost a half-80%,sga_target. Fault day business changes, session number increased by one times, reached 1000, memory tension, used to swap space.

Workaround: Find time to close the database, reconfigure Hugepages, reboot the database to observe, memory consumption is less, and before the hugepages is not turned on is the order of magnitude contrast. Hugepage can reduce the burden of the CPU, but also reduces the consumption of system memory, generally recommended Linux database system configuration Hugepage (especially memory large, session more).

About opening hugepages and closing, refer to: http://blog.csdn.net/haibusuanyun/article/details/20697371

About Linux 6 off; http://blog.csdn.net/haibusuanyun/article/details/41983497

number of sessions over 600 hours
[Email protected]* ~]$ ps-ef|grep local| Wc-l
613
[Email protected]* ~]$ ps-ef|grep local| Wc-l
647
[Email protected] ~]$ free-m
Total used free shared buffers Cached
mem:257927 255079 2847 0 64 148001
-/+ buffers/cache:107013 150914
swap:31999 13738 18261
[Email protected] ~]$ cat/proc/meminfo |grep PageT
pagetables:94353044 KB
[Email protected] ~]$ free-m
Total used free shared buffers Cached
mem:257927 255182 2745 0 64 147743
-/+ buffers/cache:107373 150553
swap:31999 13981 18018
[Email protected] ~]$ Ps-ef|grep local| Wc-l
654
[Email protected]~]$ cat/proc/meminfo |grep PageT
pagetables:95038204 KB

When the number of sessions is 1000,
[Email protected] ~]$ cat/proc/meminfo |grep PageT
pagetables:110855888 KB
[Email protected] ~]$ Ps-ef|grep local| Wc-l
1016

Additional usage after configuring Hugepages

[Email protected] ~]$ cat/proc/meminfo |grep Page
pagetables:164464 KB
[Email protected]~]$ ps-ef|grep local|wc-l
429

A tragedy caused by the Hugepages ORACLE session surge was not turned on