2.實踐配置

A. Oracle10g配置

平臺：

hw：x86_64

os：RHEL5.4

kernel： 2.6.18-164.el5

db：oracle10.2

1). 用root用戶配置文件“/etc/security/limits.conf”，添加memlock，他的大小略小于總內存，例如：64GB，配置如下：

[root@skatedb ~]# vi /etc/security/limits.conf

##skate add

*?? soft?? memlock??? 60397977

*?? hard?? memlock??? 60397977

##skate add

2).用oracle重新登錄，檢查memlock的設置是否生效[oracle@skatedb ~]$ ulimit -l

60397977

3).確定所有的oracle數據庫實例都啟動,包括asm實例，然后用如下腳本計算參數“vm.nr_hugepages"的大小

------------------hugepages_settings.sh----------------------------

#!/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

-----------------------hugepages_settings.sh-----------------------

也可以手工計算nr_hugepages>=SGA_Target/Hugepagesize

然后把nr_hugepages追加寫入文件“/etc/sysctl.conf”，假如這里計算的nr_hugepages=15000

[root@skatedb ~]# vi /etc/sysctl.conf

##skate add

vm.nr_hugepages=15000

##skate add

使其修改生效

[root@skatedb ~]# sysctl -p

4).停止oracle數據庫，reboot服務器

5).檢查hugepage是否生效

[root@skatedb ~]# grep HugePages /proc/meminfo

HugePages_Total: 15000

HugePages_Free:?? 4779

HugePages_Rsvd:?? 4676

如果HugePages_Total=HugePages_Free，說明HugePages配置沒起作用。

B. oracle11g配置

平臺：

hw：x86_64

os：RHEL5 (Taroon)

kernel： 2.6.18-194.el5

db：oracle 11.2.0.2.0

oracle11g的新特性是通過啟用參數MEMORY_TARGET/MEMORY_MAX_TARGET，啟用AMM的oracle11g的所有SGA內存的分配方式都是通過在/dev/shm下創建文件，而已這種方式分配的sga是不啟用hugepage的，AMM和hugepage是不兼容的，因為/dev/shm是tmpfs文件系統，而tmpfs文件系統是不支持AMM動態調整sga大小的，所以要想使用hugepage的特性就要關閉AMM特性。兩個如何取舍就看你了。

停止oracle11g的AMM直接把MEMORY_MAX_TARGET和MEMORY_TARGET設置為‘0’，就抱如下的錯誤

ORA-00843: Parameter not taking MEMORY_MAX_TARGET into account

ORA-00849: SGA_TARGET 35433480192 cannot be set to more than MEMORY_MAX_TARGET 0.

ORA-01078: failure in processing system parameters

如果只設置MEMORY_TARGET=0，hugepage是不起作用的。所以采用不設置這兩個參數，就可以關閉oracle11g的AMM了。創建pfile.ora文件，然后在文件里刪除兩個參數"MEMORY_TARGET/MEMORY_MAX_TARGET"。就是因為這個關閉AMM的地方測試了半天，才通過。

停止了oracle11g的AMM后，在按著oracle10g的配置方法就可以啟動hugepage了。

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