Oracle诊断案例-SGA与Swap之一

发现物理内存仅为1G，free部分为34M，交换区使用了752M，仅10M free
系统内存严重不足，Swap区不足

8. 检查数据库的SGA设置

发现SGA设置为: 622299344 bytes
接近600M

wapplatform:/>su - oracle
Sun Microsystems Inc. SunOS 5.8 Generic Patch October 2001
You have new mail.
/export/home1/oracle>sqlplus "/ as sysdba"

SQL*Plus: Release 9.2.0.3.0 - Production on 星期二 3月 23 14:02:30 2004

Copyright (c) 1982, 2002, Oracle Corporation. All rights reserved.

连接到:
Oracle9i Enterprise Edition Release 9.2.0.3.0 - 64bit Production
With the Partitioning, OLAP and Oracle Data Mining options
JServer Release 9.2.0.3.0 - Production

SQL> show sga

Total System Global Area 622299344 bytes
Fixed Size 731344 bytes
Variable Size 268435456 bytes
Database Buffers 352321536 bytes
Redo Buffers 811008 bytes
SQL>

对于RAM小于1G的系统，Dedicated模式下,Oracle的SGA一般不应超过1/2物理内存.

9.第一步调整
减小SGA，为系统保留足够的内存.

10.增加swap区

wapplatform:/>df -k
文件系统 千字节 用了 可用 容量 挂接在
/dev/dsk/c0t1d0s0 3099093 105421 2931691 4% /
/dev/dsk/c0t2d0s0 10325760 8359637 1862866 82% /usr
/proc 0 0 0 0% /proc
fd 0 0 0 0% /dev/fd
mnttab 0 0 0 0% /etc/mnttab
/dev/dsk/c0t1d0s3 1018382 285914 671366 30% /var
swap 3904 24 3880 1% /var/run
swap 3936 56 3880 2% /tmp
/dev/dsk/c0t1d0s5 1671823 459202 1162467 29% /opt
/dev/dsk/c0t2d0s7 7087473 6068462 948137 87% /export/home
/dev/dsk/c2t1d0s7 17413250 15900222 1338896 93% /export/home2
/dev/dsk/c0t3d0s7 17413250 13749782 3489336 80% /export/home1
/dev/dsk/c0t1d0s1 771110 382410 334723 54% /usr/openwin
/export/home/wapgw/luke
7087473 6068462 948137 87% /home/wap

wapplatform:/var/swap>cd /export/home1
wapplatform:/export/home1>ls
TT_DB lost+found oracle oracli9
wapplatform:/export/home1>mkdir swap
wapplatform:/export/home1>cd swap
wapplatform:/export/home1/swap>mkfile -v 1g swapfile1
swapfile1 1073741824 bytes
wapplatform:/export/home1/swap>id
uid=0(root) gid=1(other)
wapplatform:/export/home1/swap>swap -a /export/home1/swap/swapfile1
wapplatform:/export/home1/swap>swap -s
总数：分配了 623160k 字节 + 保留 162704k = 已使用 785864k，1010936k 可用

11.连接测试

系统恢复正常，问题解决

wapplatform:/export/home1/swap>su - oracle
Sun Microsystems Inc. SunOS 5.8 Generic Patch October 2001
You have new mail.
/export/home1/oracle>sqlplus "/ as sysdba"

SQL*Plus: Release 9.2.0.3.0 - Production on 星期四 3月 25 11:56:28 2004

Copyright (c) 1982, 2002, Oracle Corporation. All rights reserved.

连接到:
Oracle9i Enterprise Edition Release 9.2.0.3.0 - 64bit Production
With the Partitioning, OLAP and Oracle Data Mining options
JServer Release 9.2.0.3.0 - Production

SQL> exit
从Oracle9i Enterprise Edition Release 9.2.0.3.0 - 64bit Production
With the Partitioning, OLAP and Oracle Data Mining options
JServer Release 9.2.0.3.0 - Production中断开
/export/home1/oracle>top

last pid: 5372; load averages: 0.25, 0.22, 0.29

11:57:58
148 processes: 137 sleeping, 9 zombie, 2 on cpu
CPU states: 98.8% idle, 0.2% user, 0.7% kernel, 0.2% iowait, 0.0% swap
Memory: 1024M real, 17M free, 824M swap in use, 934M swap free

PID USERNAME THR PRI NICE SIZE RES STATE TIME CPU COMMAND
5363 root 1 58 0 2680K 1736K sleep 0:00 0.24% top
5370 oracle 1 58 0 514M 469M sleep 0:00 0.18% oracle
5366 oracle 1 28 0 514M 469M sleep 0:00 0.11% oracle
5341 oracle 1 58 0 2680K 1736K cpu/2 0:00 0.10% top
5372 oracle 1 48 0 61M 3288K cpu/3 0:00 0.06% oracle
1288 oracle 1 48 0 514M 468M sleep 5:33 0.05% oracle
607 root 12 48 0 2768K 2312K sleep 1:48 0.03% mibiisa
25075 oracle 1 48 0 17M 7208K sleep 0:16 0.02% tnslsnr
1278 oracle 15 58 0 522M 466M sleep 0:49 0.02% oracle
374 root 11 53 0 3504K 2888K sleep 0:16 0.01% nscd
1280 oracle 19 58 0 518M 466M sleep 0:28 0.00% oracle
5361 root 1 46 0 1024K 680K sleep 0:00 0.00% sleep
5362 root 1 46 0 1024K 680K sleep 0:00 0.00% sleep
5469 root 1 36 0 1952K 1176K sleep 30:09 0.00% monithttp
4167 oracle 1 40 0 515M 471M sleep 29:38 0.00% oracle

问题总结:

Oracle数据库问题的解决从来就离不开操作系统

很多时候我们必须通过操作系统一级的手段来诊断并解决问题.

关于操作系统

一般Swap区的推荐值为2XRAM
如果Ram很大，不一定非要把Swap设置为2xSwap
但是通常至少设置Swap = Ram

如果Swap区过小，在系统繁忙期间
产生大量交换无法换到磁盘，就会出现问题.
如本案例就是这样。

另外，如果系统Ram较小
通常设置SGA < 1/2 Ram

要为Server process及OS保留足够的内存空间.

上一页  [1] [2] [3] [4] 

Copyright ＠ 2007-2012 敏韬网(敏而好学，文韬武略--MinTao.Net)（学习笔记） Inc All Rights Reserved.
闵涛 E_mail:admin@mintao.net(欢迎提供学习资源)

鄂公网安备 42011102001154号

站长：MinTao ICP备案号：鄂ICP备11006601号-18