标签：handles which mic max sim rac back sql creat
[root@db2 ~]# lsof -n | grep /dev/shm | wc -l34693
[root@db2 ~]# ls -l /dev/shm | wc -l495
[root@db2 ~]# ps -ef | grep ora_smon | grep -v greporacle 13984 1 0 Dec07 ? 00:17:30 ora_smon_db2[root@db2 ~]# lsof | grep 13984 | grep -v grep | wc -l456
[root@db2 ~]# ps -ef | grep -v grep | grep -i ora_ | wc -l76
下列文章来自（MOS:1321306.1）
1) Let‘s use a test database (11.1.0.7) to demonstrate how Automatic Memory Management uses file descriptors and why there are so many Open File descriptors.
Number of files in /dev/shm
There are 203 files ( 4 MB size, which is the granule size) （内存粒度的说明见oracle内存粒度的说明）
This is approximately MEMORY_TARGET/4MB
Since MEMORY_TARGET < 1 GB, 203 x 4 MB files are created
For a larger MEMORY_TARGET, the number of files in /dev/shm = MEMORY_TARGET/granule size
See Note 947152.1 How to determine granule size.
Number of open files descriptors
There are 4872 open files handles why ?
After starting the 11.1.0.7 database, 24 background processes were created
UNIX> ps -ef | grep -i <database name> | wc -l
24
Each background process open 203 files x 24 = 4872
UNIX> lsof -n | grep /dev/shm | wc -l
4872
总结：
ls -l /dev/shm | wc -l open files = MEMORY_TARGET/granule size
lsof -n | grep /dev/shm | wc -l open file descriptos = open files*进程数
标签：handles which mic max sim rac back sql creat
原文地址：http://www.cnblogs.com/haoxiaoyu/p/f53e68d2d09ba861dbdc1fa521f1a54d.html
