Linux

Posted by BlueFat on Monday, May 14, 2018

Linux Tcpdump抓包

Linux Tcpdump

tcpdump 是一款强大的网络抓包工具，它使用 libpcap 库来抓取网络数据包，这个库在几乎在所有的 Linux/Unix 中都有。熟悉 tcpdump 的使用能够帮助你分析调试网络数据，本文将通过一个

Posted by BlueFat on Friday, May 4, 2018

Linux内存占用过高排查

Linux Memory Sort

查看内存情况 free # 按单位KB显示,即free -k free -m # 按单位MB显示 free -h # 按单位GB显示 [root@ha ~]# free -h total used free shared buff/cache available Mem: 3.8G 2.5G 111M 179M 1.2G 822M Swap: 0B 0B 0B total: 总计物理内存

Posted by BlueFat on Friday, April 27, 2018

Keepalived配置文件详解

Keepalived conf

Keepalived的配置文件可以分为三块：全局定义块：对整个 Keepalive 配置生效的，不管是否使用 LVS； VRRP 实例定义块：是 Keepalived 的核心；虚拟服务器（LVS

Posted by BlueFat on Wednesday, February 7, 2018

Nginx 使用tmpfs缓存优化读写速度

Nginx tmpfs

tmpfs : 使用内存作为Linux磁盘文件,用于缓存读写。操作 vim /etc/fstab tmpfs /tmpfs_cache tmpfs size=2G,noatime,nodiratime 0 0 挂载 mkdir /tmpfs_cache mount -a 效果 df -h | grep /tmpfs_cache tmpfs 2.0G 216K 2.0G 1% /tmp 现在就可以将nginx 缓存目录指

Posted by BlueFat on Friday, January 5, 2018

Mysql 主从延迟

Mysql_slave_delay

innodb_flush_log_at_trx_commit和sync_binlog参数详解案例收到邮件报警，mysql主从延迟>1h

Posted by BlueFat on Tuesday, November 28, 2017

Mysql导入导出太慢优化

Mysql Import Too Slow

MySQL导出的SQL语句在导入时有可能会非常非常慢，经历过导入仅45万条记录，竟用了近3个小时。在导出时合理使用几个参数，可以大大加快导入

Posted by BlueFat on Monday, November 27, 2017

SWAP 常见问题分析和性能调优配置实践小结

Swap

前言 SWAP 内存交换分区对大家来说是一个经常被忽视的细节，如果大家对 SWAP 配置不是很熟悉可以参考文章内提到的 Red Hat SWAP SPACE 最佳实践配置链接。本文主要分享 SWAP 的

Posted by BlueFat on Monday, November 13, 2017

常用shell命令整理

Common Shell

# 通过此命令查看内存被哪些进程占用（单位是 MByte）,输出 PID 与内存占用大小，通过 PID 可以找到对应进程 for i in `cd /proc;ls | grep "^[0-9]" | awk '$0 >100'` ;do awk '/Swap:/{a=a+$2}END{print '"$i"',a/1024"M"}' /proc/$i/smaps ;done 2>&1 |

Posted by BlueFat on Monday, November 13, 2017

使用 MegaCli64 快速查看 RAID 和定位故障硬盘实践

Megacli64

DELL 通过MegaCLI提取RAID控制器日志 How to: Install LSI Command Line Tool LSI hardware RAID has a command line tool to manage RAID related commands and configuration. It is called MegaCLI. MegaCLI is available at broadcom doc downloads. Use the following to download MegaCLI: wget https://docs.broadcom.com/docs-and-downloads/raid-controllers/raid-controllers-common-files/8-07-14_MegaCLI.zip Unzip the MegaCLI file: unzip 8-07-14_MegaCLI.zip cd Linux

Posted by BlueFat on Thursday, October 12, 2017

Shell判断输入变量或者参数是否为空

Shell Judge Empty

判断变量为空 if [ ! -n "$word" ] ;then echo "you have not input a word" else echo "the word you input is $word" fi 直接判断 if [ ! "$word" ] ;then echo "you have not input a word" else echo "the word you input is $word" fi 使用test判断 if test -z "$word" ;then echo "you

Posted by BlueFat on Saturday, August 19, 2017

Linux用户登录次数限制、开启连接超时、开启审计日志

Linux Login Limit

https://blog.csdn.net/qq_43164571/article/details/119234593?spm=1001.2014.3001.5502

Posted by BlueFat on Sunday, May 28, 2017

LVM 逻辑卷管理配置

Lvm

前言 Logical Volume Manager (LVM)，逻辑卷管理 LVM 是一个多才多艺的硬盘系统工具，无论在 Linux 或者其他类似的系统，都是非常的好用。传统分区使用固定大小分区，重新调

Posted by BlueFat on Wednesday, May 17, 2017

解决nf_conntrack: table full, dropping packet

Nf_conntrack Table Full Dropping Packet

系统连接数高的时候，机子出现掉包，查看日志发现报错，nf_conntrack: table full, dropping packet，解决办法就是调整参数稳妥的临时处理办法： vi

Posted by BlueFat on Monday, March 27, 2017

Sunday Blog

tcpdump 抓包使用小结

Tcpdump