June 20, 2006
新书名称确定－《深入浅出Oracle》
作者:eygle
出处:http://blog.eygle.com
在经历了艰难的取舍和选择之后，书名最终确定为《深入浅出Oracle-DBA入门、进阶与诊断案例》，这个名字基本上涵盖了本书的内容和特色。
目前书稿已经交付出版社，正在进行紧张的审阅和排版工作，希望可以尽快的和大家见面。
再次感谢大家的关注与支持！
Posted by eygle at 3:47 PM | Comments (0) | TrackBack
Dell的2850 + Oracle10gR2 I/O性能测试
作者:eygle
出处:http://blog.eygle.com
前几天帮朋友安装了一套Oracle10gR2的环境，顺便简单测试了一下IO性能。
机器是Dell的2850，三块硬盘的Raid5。
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[oracle@order ~]$ sqlplus eygle/eygle SQL*Plus: Release 10.2.0.2.0 - Production on Fri Jun 16 11:29:49 2006 Connected to: |
SGA设置如下:
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SQL> show sga Total System Global Area 2483027968 bytes |
插入数据测试性能:
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SQL> create table t as select * from dba_objects where 1=0; Table created. SQL> begin PL/SQL procedure successfully completed. |
通过iostat观察IO性能，以下简要的几个采样显示：
在iowait达到25.24%时，系统的IO写入能力可以达到18M左右。
在iowait达到28.23%时，系统的IO写入能力可以达到48M左右。
而CPU的idle值都在60%以上，说明CPU仍然有相当空闲，IO仍然是主要瓶颈。
但是这个IO性能也已经不错了，SCSI的硬盘，能够满足一般业务的需求了。
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[oracle@xcstat ~]$ iostat -k 5|grep -v "0.00 0.00 0.00" avg-cpu: %user %nice %sys %iowait %idle Device: tps kB_read/s kB_wrtn/s kB_read kB_wrtn avg-cpu: %user %nice %sys %iowait %idle Device: tps kB_read/s kB_wrtn/s kB_read kB_wrtn |
平均IO写入速度为:19183.18945 kB_wrtn/s
最大IO写入速度为:48107.41 kB_wrtn/s
最小IO写入速度为:978 kB_wrtn/s
简单的测试，记录些简单的数据供参考。
Posted by eygle at 11:44 AM | Comments (5) | TrackBack
隐含参数_disable_logging的几点说明
作者:eygle
出处:http://blog.eygle.com
在很久以前,曾经介绍过Oracle的一个内部隐含参数_disable_logging,看到有朋友论述这个参数,今天忍不住做一点补充说明.
1.当然,隐含有风险,设置请谨慎.
2.最初在9.2.0.6 Solaris版本上,设置该参数会触发Bug:3868748 使得数据库无法启动.
从警告日志中,通常可以获得的错误提示是:
| ORA-07445: exception encountered: core dump [kcrfwcint()+1625] [SIGFPE] [Integer divide by zero] [0x828739D] [] [] |
但是好在这个参数是动态的,在存在Bug版本中,我们可以修改数据库当前值来进行测试:
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SQL> alter system set "_disable_logging"=true scope=memory; System altered. |
3.这个Bug的影响范围并非全部,9.2.0.6之下,Oracle9.2.0.5,Oracle9.2.0.4等,都不受这个Bug影响.Oracle声称的修正该Bug的版本是Oracle10gR2(我未验正).
4.这个参数在Oracle9.2.0.4版本的Linux/Solaris上是不存在这个Bug的.在我的环境中经过验证,过程请参考(附注1).
5.在归档模式下,设置该参数会导致日志文件损坏.因为在设置该参数与归档原则违背，归档进程无法识别该日志文件格式，会将该日志文件标记为损坏.所以需要谨慎测试,具体请参考(附注2).
附注1:Solaris Oracle9.2.0.4设置测试过程:
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$ sqlplus "/ as sysdba" SQL*Plus: Release 9.2.0.4.0 - Production on Thu Apr 13 22:51:24 2006 Copyright (c) 1982, 2002, Oracle Corporation. All rights reserved.
SQL> show parameter disa NAME TYPE VALUE System altered. SQL> shutdown immediate; Total System Global Area 286755168 bytes NAME TYPE VALUE BANNER |
附注2:归档模式下,该参数会导致日志文件损坏.
设置该参数后,切换日志:
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SQL> archive log list; System altered. SQL> select group#,status from v$Log; GROUP# STATUS SQL> show parameter disable NAME TYPE VALUE |
此时可以在警告日志中看到日志损坏的错误信息:
| Thu Apr 13 23:33:25 2006 ARC0: Evaluating archive log 2 thread 1 sequence 23 ARC0: Beginning to archive log 2 thread 1 sequence 23 Creating archive destination LOG_ARCHIVE_DEST_1: '/opt/oracle/oradata/conner/archive/1_23.dbf' ARC0: Log corruption near block 3849 change 0 time ? ARC0: All Archive destinations made inactive due to error 354 Thu Apr 13 23:33:25 2006 Errors in file /opt/oracle/admin/conner/bdump/conner_arc0_21506.trc: ORA-00354: corrupt redo log block header ORA-00353: log corruption near block 3849 change 0 time 04/13/2006 21:13:03 ORA-00312: online log 2 thread 1: '/opt/oracle/oradata/conner/redo02.log' ARC0: Archiving not possible: error count exceeded ARC0: Failed to archive log 2 thread 1 sequence 23 ARCH: Archival stopped, error occurred. Will continue retrying Thu Apr 13 23:33:26 2006 ORACLE Instance conner - Archival Error ARCH: Connecting to console port... Thu Apr 13 23:33:26 2006 ORA-16038: log 2 sequence# 23 cannot be archived ORA-00354: corrupt redo log block header ORA-00312: online log 2 thread 1: '/opt/oracle/oradata/conner/redo02.log' ARCH: Connecting to console port... ARCH: Thu Apr 13 23:33:26 2006 ORA-16038: log 2 sequence# 23 cannot be archived ORA-00354: corrupt redo log block header ORA-00312: online log 2 thread 1: '/opt/oracle/oradata/conner/redo02.log' |
Posted by eygle at 11:27 AM | Comments (0) | TrackBack