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Linux mysql 优化

May 28, 2012 MYSQL, performance No comments

linux mysql

一、修改内核参数
1.1、编辑/etc/sysctl.conf
vi /etc/sysctl.conf

net.ipv4.tcp_max_syn_backlog = 65536
net.core.netdev_max_backlog = 65536
net.core.somaxconn = 32768

net.core.wmem_default = 8388608
net.core.rmem_default = 8388608
net.core.rmem_max = 16777216
net.core.wmem_max = 16777[……]

11g 密码延迟登陆导致 library cache lock

May 24, 2012 11g, oracle No comments

前阵子刚写过11g密码延迟登陆的新特性,11g oracle在登陆密码输入错误时候不会立刻中断这个连接而会递增等待时间,这有可能在失败登陆N次以后达到一个很长的阀值（10s),从而导致session 大量积压导致问题的严重化，今天就碰到了问题,PMS team在转换密钥的时候出现了问题，应用一直狂连数据库，但是由于密码不正确,延迟登陆导致latch无法释放：

[oracle@db-38 ~]$ ora active
17:15:10 up 153 days, 7:09, 4 users, load average: 4.05, 2.06, 1.[……]

Scripts: report the index fragmentation status

May 14, 2012 maintain, oracle No comments

/* ************************************************************* */
/* Index Fragmentation Status (idsfrag.sql): */
/* */
/* This script will report the index fragmentation status */
/* for a schema.[……]

MySQL Plug-in for EM 12c

May 11, 2012 MYSQL No comments

来自pythian mysql project

With this plug-in, a DBA can add a new MySQL target just as they can an Oracle database. Oracle Enterprise Manager Agent doesn’t have to be running on the same host as the monitored MySQL database. I.e., remote monitoring of the MySQL database using one or two agents is[……]

11G New feature: Failed Logon Delays

April 27, 2012 11g, oracle 4 comments 11g new feature

在pub上看到一个不错的帖子 oracle 11g password delay

对这个特性做如下说明

Failed Logon Delays

A hacker may attempt a brute force hack to break into your Oracle Database. This is where they try constant logons to the database using some form of a word list. To try to make brute force hacking more difficult, Ora[……]

11gR2 rac ora.asm error (ASM)

April 26, 2012 maintain, oracle, RAC No comments 11g new feature, asm

ASM – ora.asm error

11.2.0.3 RAC CRS 无法启动

[ohasd(25286)]CRS-2112:The OLR service started on node db-41.
2012-04-25 14:46:13.120
[ohasd(25286)]CRS-1301:Oracle High Availability Service started on node db-41.
2012-04-25 14:46:13.120
[ohasd(25286)]CRS-8017:location: /etc/oracle/lastg[……]

ASM Preferred mirror Read

April 25, 2012 oracle, RAC 2 comments asm

ASM Preferred mirror Read

Introduction

The concept of the Preferred Read is not a new idea, but is now implemented in Oracle’s ASM volume
management in Oracle 11g.The concept is to read from the storage that can present the needed data at a lower
latency. Initially, this was designe[……]