今天在调整线上数据库，服务器增大内存后，数据库需要调整大页，这其中发现这个过程中总是调整的不完全，这里做一个简单总结。
1.现有环境是oracle 11.2.0.1,需要关闭AMM,设置memory_max_target和memory_target成0表示不成功
SQL> show parameter memory_max_target
NAME TYPE VALUE
----------------- ------------ ------------
memory_max_target big integer 0
SQL> show parameter memory_target
NAME TYPE VALUE
----------------- ------------ ------------
memory_target big integer 0
2.运行脚本 hugepages_settings.sh
这个脚本是Oracle官方提供的,运行这个脚本即可得出大页的设置值，参考metalink(文档 ID 401749.1),脚本如下：
#!/bin/bash
#
# hugepages_settings.sh
#
# Linux bash script to compute values for the
# recommended HugePages/HugeTLB configuration
#
# Note: This script does calculation for all shared memory
# segments available when the script is run, no matter it
# is an Oracle RDBMS shared memory segment or not.
#
# This script is provided by Doc ID 401749.1 from My Oracle Support
# http://support.oracle.com
# Welcome text
echo "
This script is provided by Doc ID 401749.1 from My Oracle Support
(http://support.oracle.com) where it is intended to compute values for
the recommended HugePages/HugeTLB configuration for the current shared
memory segments. Before proceeding with the execution please make sure
that:
* Oracle Database instance(s) are up and running
* Oracle Database 11g Automatic Memory Management (AMM) is not setup
(See Doc ID 749851.1)
* The shared memory segments can be listed by command:
# ipcs -m
Press Enter to proceed..."
read
# Check for the kernel version
KERN=`uname -r | awk -F. '{ printf("%d.%d\n",$1,$2); }'`
# Find out the HugePage size
HPG_SZ=`grep Hugepagesize proc/meminfo | awk '{print $2}'`
# Initialize the counter
NUM_PG=0
# Cumulative number of pages required to handle the running shared memory segments
for SEG_BYTES in `ipcs -m | awk '{print $5}' | grep "[0-9][0-9]*"`
do
MIN_PG=`echo "$SEG_BYTES/($HPG_SZ*1024)" | bc -q`
if [ $MIN_PG -gt 0 ]; then
NUM_PG=`echo "$NUM_PG+$MIN_PG+1" | bc -q`
fi
done
RES_BYTES=`echo "$NUM_PG * $HPG_SZ * 1024" | bc -q`
# An SGA less than 100MB does not make sense
# Bail out if that is the case
if [ $RES_BYTES -lt 100000000 ]; then
echo "***********"
echo "** ERROR **"
echo "***********"
echo "Sorry! There are not enough total of shared memory segments allocated for
HugePages configuration. HugePages can only be used for shared memory segments
that you can list by command:
# ipcs -m
of a size that can match an Oracle Database SGA. Please make sure that:
* Oracle Database instance is up and running
* Oracle Database 11g Automatic Memory Management (AMM) is not configured"
exit 1
fi
# Finish with results
case $KERN in
'2.4') HUGETLB_POOL=`echo "$NUM_PG*$HPG_SZ/1024" | bc -q`;
echo "Recommended setting: vm.hugetlb_pool = $HUGETLB_POOL" ;;
'2.6') echo "Recommended setting: vm.nr_hugepages = $NUM_PG" ;;
*) echo "Unrecognized kernel version $KERN. Exiting." ;;
esac
# End
执行这个脚本得出大页的设置值 66563
[oracle@ams_odbs_26_21 ~]$ chmod +x hugepages_settings.sh
[oracle@ams_odbs_26_21 ~]$ sh hugepages_settings.sh
hugepages_settings.sh: line 1: [oracle@newdb2: command not found
This script is provided by Doc ID 401749.1 from My Oracle Support
(http://support.oracle.com) where it is intended to compute values for
the recommended HugePages/HugeTLB configuration for the current shared
memory segments. Before proceeding with the execution please make sure
that:
* Oracle Database instance(s) are up and running
* Oracle Database 11g Automatic Memory Management (AMM) is not setup
(See Doc ID 749851.1)
* The shared memory segments can be listed by command:
# ipcs -m
Press Enter to proceed...
Recommended setting: vm.nr_hugepages = 66563
3.更改系统参数
vi /etc/sysctl.conf
kernel.shmmax = 139586437120
kernel.shmall = 34078720
kernel.shmmni = 4096
vm.nr_hugepages = 66564
kernel.shmmax：单个共享内存段的最大值，要大于oracle数据库中的SGA的大小， 单位是字节
kernel.shmall： 共享内存页数,Linux 共享内存页大小为4KB 这个值等于kernel.shmmax/kernel.shmmni
kernel.shmmni ：享内存段的最大数量,默认4K 就是4096
修改完成之后，使用命令 sysctl -p 使得参数生效。
附加：sysctl -p 命令结束后发现的问题：
问题 ：sysctl -p 的出的结果中发现报错
error: "net.bridge.bridge-nf-call-ip6tables" is an unknown key
error: "net.bridge.bridge-nf-call-iptables" is an unknown key
error: "net.bridge.bridge-nf-call-arptables" is an unknown key
解决方法：加载模块后解决
modprobe bridge
修改limits.conf文件，这个文件限制着用户可以使用的最大文件数，最大线程，最大内存等资源使用量，添加最后两行
(memlock 单位是KB) 必须大于sga_max_size: 130G
vi /etc/security/limits.conf
oracle soft nproc 65535
oracle hard nproc 65535
oracle soft nofile 655350
oracle hard nofile 655350
oracle soft stack 10240
oracle soft memlock 136314880
oracle hard memlock 136314880
还有一个文件也需要修改，/etc/security/limits.d/90-nproc.conf (这个文件在Centos6.5中是90-nproc.conf,在7之后就是20-nproc.conf)
cd /etc/security/limits.d/
[root@ams_odbs_26_21 limits.d]# vi 90-nproc.conf
# Default limit for number of user's processes to prevent
# accidental fork bombs.
# See rhbz #432903 for reasoning.
* soft nproc 65535
root soft nproc unlimited
修改完成之后,切换到oracle用户下查看是否生效
[oracle@ams_odbs_26_21 ~]$ ulimit -a
core file size (blocks, -c) 0
data seg size (kbytes, -d) unlimited
scheduling priority (-e) 0
file size (blocks, -f) unlimited
pending signals (-i) 2059863
max locked memory (kbytes, -l) 136314880
max memory size (kbytes, -m) unlimited
open files (-n) 655350
pipe size (512 bytes, -p) 8
POSIX message queues (bytes, -q) 819200
real-time priority (-r) 0
stack size (kbytes, -s) 10240
cpu time (seconds, -t) unlimited
max user processes (-u) 65535
virtual memory (kbytes, -v) unlimited
file locks (-x) unlimited
4.重启数据库,大页才会被使用,重启过程省略。
5.查看大页是否被使用
[oracle@ams_odbs_26_21 ~]$ cat /proc/meminfo |grep -i HugePage
AnonHugePages: 681984 kB
HugePages_Total: 66564
HugePages_Free: 63228
HugePages_Rsvd: 63224
HugePages_Surp: 0
Hugepagesize: 2048 kB
HugePages_Total: 66564 —总共66564页
HugePages_Free: 63228 —空闲63228页，即当前大页被使用了66564-63228=3236页，即被用了3236*2M=6472M，小于sga_target。
HugePages_Rsvd: 63224 —操作系统承诺给Oracle预留63224页
Hugepagesize: 2048 kB –每页是2M，不可修改
