Linux釋放記憶體及手動釋放Oracle共享記憶體段

$ free -m
free記憶體減少到幾十兆，系統執行緩慢
 
執行sync將dirty的內容寫回硬碟
$sync
 
drop_caches的詳細文件如下：
Writing to this will cause the kernel to drop clean caches, dentries and inodes from memory, causing that memory to become free.
To free pagecache:
* echo 1 > /proc/sys/vm/drop_caches
To free dentries and inodes:
* echo 2 > /proc/sys/vm/drop_caches
To free pagecache, dentries and inodes:
* echo 3 > /proc/sys/vm/drop_caches
As this is a non-destructive operation, and dirty objects are notfreeable, the user should run "sync" first in order to make sure allcached objects are freed.
This tunable was added in 2.6.16.
 
修改/etc/sysctl.conf 新增如下選項後就不會記憶體持續增加
vm.dirty_ratio = 1
vm.dirty_background_ratio=1
vm.dirty_writeback_centisecs=2
vm.dirty_expire_centisecs=3
vm.drop_caches=3
vm.swappiness =100
vm.vfs_cache_pressure=163
vm.overcommit_memory=2
vm.lowmem_reserve_ratio=32 32 8
kern.maxvnodes=3

 
手動刪除Oracle共享記憶體段
$ ps -ef |grep $ORACLE_SID|grep -v grep|awk '{print $2}' | xargs kill -9
$ ipcs -m | grep oracle | awk '{print $2}' | xargs ipcrm shm

--增加LINUX虛擬記憶體，11g由於設定memory_target引數而共享記憶體過小，無法啟動時報ORA-00845
mount -t tmpfs shmfs -o size=32g /dev/shm

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