详解keepalived配置和使用
详解keepalived配置和使用
一、keepalived简介:
keepalived是一个类似于layer3, 4 & 5交换机制的软件,也就是我们平时说的第3层、第4层和第5层交换。Keepalived的作用是检测web服务器的状态,如果有一台web服务器死机,或工作出现故障,Keepalived将检测到,并将有故障的web服务器从系统中剔除,当web服务器工作正常后Keepalived自动将web服务器加入到服务器群中,这些工作全部自动完成,不需要人工干涉,需要人工做的只是修复故障的web服务器。
工作原理
Layer3,4&5工作在IP/TCP协议栈的IP层,TCP层,及应用层,原理分别如下:
Layer3:Keepalived使用Layer3的方式工作式时,Keepalived会定期向服务器群中的服务器发送一个ICMP的数据包(既我们平时用的Ping程序),如果发现某台服务的IP地址没有激活,Keepalived便报告这台服务器失效,并将它从服务器群中剔除,这种情况的典型例子是某台服务器被非法关机。Layer3的方式是以服务器的IP地址是否有效作为服务器工作正常与否的标准。
Layer4:如果您理解了Layer3的方式,Layer4就容易了。Layer4主要以TCP端口的状态来决定服务器工作正常与否。如web server的服务端口一般是80,如果Keepalived检测到80端口没有启动,则Keepalived将把这台服务器从服务器群中剔除。
Layer5:Layer5就是工作在具体的应用层了,比Layer3,Layer4要复杂一点,在网络上占用的带宽也要大一些。Keepalived将根据用户的设定检查服务器程序的运行是否正常,如果与用户的设定不相符,则Keepalived将把服务器从服务器群中剔除。
二、实验步骤:
1.创建管理节点在node1上,建立双机互信node1和node2,然后同步时间,安装keepalived
[root@node1~]# ansible all -m yum -a 'name=keepalived state=present'
[root@node1keepalived]# rpm -qc keepalived /etc/keepalived/keepalived.conf//生成的主配置文件 /etc/sysconfig/keepalived
2.在node1上配置文件需要做一下修改
global_defs{notification_email {root@localhost //收邮件人,可以定义多个}notification_email_from kaadmin@localhost //发邮件人可以伪装smtp_server 127.0.0.1 //发送邮件的服务器地址smtp_connect_timeout 30 //连接超时时间router_id LVS_DEVEL
}
vrrp_instanceVI_1 { //每一个vrrp_instance就是定义一个虚拟路由器的 state MASTER //由初始状态状态转换为master状态 interface eth0 virtual_router_id 51 //虚拟路由的id号,一般不能大于255的 priority 100 //初始化优先级 advert_int 1 //初始化通告 authentication { //认证机制 auth_type PASS auth_pass 1111 //密码 } virtual_ipaddress { //虚拟地址vip 172.16.2.8 } }
3.把配置文件复制到node2上一份,并修改初始状态和优先级
[root@node1keepalived]# scp keepalived.conf node2:/etc/keepalived/
[root@node2~]# cd /etc/keepalived/ [root@node2keepalived]# ls keepalived.conf [root@node2keepalived]# vim keepalived.conf vrrp_instanceVI_1 { state BACKUP //初始化状态 interface eth0 virtual_router_id 51 priority 99 //优先级,一定要比master的优先级要低 advert_int 1 authentication { auth_type PASS auth_pass 1111 } virtual_ipaddress { 172.16.2.8 } }
在node1上开始启动服务[root@node1 ~]# servicekeepalived start
然后检查ip地址
[root@node1~]# ip addr show
1:lo: <LOOPBACK,UP,LOWER_UP> mtu 16436 qdisc noqueue state UNKNOWN link/loopback 00:00:00:00:00:00 brd00:00:00:00:00:00 inet 127.0.0.1/8 scope host lo inet6 ::1/128 scope host valid_lft forever preferred_lft forever 2:eth0: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc pfifo_fast stateUP qlen 1000 link/ether 00:0c:29:4e:22:fb brdff:ff:ff:ff:ff:ff inet 172.16.2.1/16 brd 172.16.255.255 scopeglobal eth0 inet 172.16.2.8/32 scopeglobal eth0 inet 172.16.10.8/16 brd 172.16.255.255 scopeglobal secondary eth0:0 inet6 fe80::20c:29ff:fe4e:22fb/64 scopelink valid_lft forever preferred_lft forever 3:pan0: <BROADCAST,MULTICAST> mtu 1500 qdisc noop state DOWN link/ether 2e:79:b3:b2:3e:31 brdff:ff:ff:ff:ff:ff
4.现在把node1的keepalived停掉
[root@node1keepalived]# service keepalived stop
Stoppingkeepalived: [ OK ]
验证node2是否把virtual_ipaddress拿走
[root@node2~]# ip addr show
1:lo: <LOOPBACK,UP,LOWER_UP> mtu 16436 qdisc noqueue state UNKNOWN link/loopback 00:00:00:00:00:00 brd00:00:00:00:00:00 inet 127.0.0.1/8 scope host lo inet6 ::1/128 scope host valid_lft forever preferred_lft forever 2:eth0: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc pfifo_fast stateUP qlen 1000 link/ether 00:0c:29:74:c7:7b brdff:ff:ff:ff:ff:ff inet 172.16.2.16/16 brd172.16.255.255 scope global eth0 inet 172.16.2.8/32 scopeglobal eth0 inet6 fe80::20c:29ff:fe74:c77b/64 scopelink valid_lft forever preferred_lft forever 3:pan0: <BROADCAST,MULTICAST> mtu 1500 qdisc noop state DOWN link/ether0a:b1:ef:7b:93:18 brd ff:ff:ff:ff:ff:ff
验证成功
可以在配置文件中手动通过vrrp_script定义一个外围的检测机制,并在vrrp_instance中通过定义track_script来追踪脚本执行过程,实现节点转移
实验测试在/etc/keepalived/keepalived.conf中做一下修改
global_defs{notification_email {root@localhost}notification_email_from kaadmin@localhostsmtp_server 127.0.0.1smtp_connect_timeout 30router_id LVS_DEVEL
}
vrrp_script chk_maintainace { //检测机制的脚本名称为chk_maintainace script "[[ -e/etc/keepalived/down ]] && exit 1 || exit 0" //可以是个脚本路径,也可以是脚本命令 interval 1 //每隔1秒中检测一次 weight -2 //优先级减2 } vrrp_instanceVI_1 { state MASTER interface eth0 virtual_router_id 51 priority 100 advert_int 1 authentication { auth_type PASS auth_pass 1111 } virtual_ipaddress { 172.16.2.8 } track_script { //调用外围脚本,追踪外围脚本执行过程 chk_maintainace } } [root@node1 keepalived]# touch down //在node1上创建down文件 [root@node1 keepalived]# ls down keepalived.conf keepalived.conf.bak
在node2上做同样的操作,但不创建down文件,之后一起重启服务
[root@node1 keepalived]# ansible all -m shell -a 'service keepalivedrestart'
node2.magedu.com| success | rc=0 >> Stoppingkeepalived: [FAILED] Startingkeepalived: [ OK ] node1.magedu.com| success | rc=0 >> Stoppingkeepalived: [ OK ] Startingkeepalived: [ OK ]
进行检测
[root@node2keepalived]# ip addr show
1:lo: <LOOPBACK,UP,LOWER_UP> mtu 16436 qdisc noqueue state UNKNOWN link/loopback 00:00:00:00:00:00 brd00:00:00:00:00:00 inet 127.0.0.1/8 scope host lo inet6 ::1/128 scope host valid_lft forever preferred_lft forever 2:eth0: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc pfifo_fast stateUP qlen 1000 link/ether 00:0c:29:74:c7:7b brdff:ff:ff:ff:ff:ff inet 172.16.2.16/16 brd172.16.255.255 scope global eth0 inet 172.16.2.8/32 scopeglobal eth0 inet6 fe80::20c:29ff:fe74:c77b/64 scopelink valid_lft forever preferred_lft forever 3:pan0: <BROADCAST,MULTICAST> mtu 1500 qdisc noop state DOWN link/ether0a:b1:ef:7b:93:18 brd ff:ff:ff:ff:ff:ff
此时将node1中/etc/keepalived/下的down删除,进行查看
[root@node1keepalived]# ls
down keepalived.conf keepalived.conf.bak
[root@node1keepalived]# rm down rm:remove regular empty file `down'? y [root@node1keepalived]# ls keepalived.conf keepalived.conf.bak [root@node1 keepalived]# ip addr show 1:lo: <LOOPBACK,UP,LOWER_UP> mtu 16436 qdisc noqueue state UNKNOWN link/loopback 00:00:00:00:00:00 brd00:00:00:00:00:00 inet 127.0.0.1/8 scope host lo inet6 ::1/128 scope host valid_lft forever preferred_lft forever 2:eth0: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc pfifo_fast stateUP qlen 1000 link/ether 00:0c:29:4e:22:fb brdff:ff:ff:ff:ff:ff inet 172.16.2.1/16 brd 172.16.255.255 scopeglobal eth0 inet 172.16.2.8/32 scopeglobal eth0 inet 172.16.10.8/16 brd 172.16.255.255scope global secondary eth0:0 inet6 fe80::20c:29ff:fe4e:22fb/64 scopelink valid_lft forever preferred_lft forever 3:pan0: <BROADCAST,MULTICAST> mtu 1500 qdisc noop state DOWN link/ether0a:bd:4f:a9:ed:67 brd ff:ff:ff:ff:ff:ff
验证成功
三、详细介绍以下四个功能实现操作
1.如何在状态转换时进行通知?
2.如何配置Ipvs?
3.如何对某特定服务做高可用
4.如何实现基于多虚拟路由的master/master模型?
1.要在状态转换是进行通知,需要定义通知脚本可以在
vrrp_sync_group{
}中定义,也可以在
vrrp_instance{
}中定义
通过man keepalived命令可以查看通知脚本定义的两种方法
第一种
# to MASTER transition
notify_master /path/to_master.sh
# to BACKUP transition
notify_backup /path/to_backup.sh
# FAULT transition
notify_fault "/path/fault.sh VG_1"
第二种
#arguments
# $1 ="GROUP"|"INSTANCE"
# $2 = name of group or instance
# $3 = target state of transition
# ("MASTER"|"BACKUP"|"FAULT")
notify /path/notify.sh
例如:
转换为MASTER的状态通知
#!/bin/bash
#
vip=172.16.2.8
contact='root@localhost' thisip=`ifconfigeth0 | awk '/inet addr:/{print $2}' | awk -F: '{print $2}'` notify(){ mailbody="vrrp transaction, $vipfloated to $thisip." subject="$thisip is to be $vipmaster" echo $mailbody | mail -s $subject $contact } notify
其他状态转换类似
下面用一个脚本notify.sh实现状态转换通知的简单示例:
#!/bin/bash
#Author: MageEdu <linuxedu@foxmail.com>
#description: An example of notify script
#
vip=172.16.2.8 contact='root@localhost' notify(){ mailsubject="`hostname` to be $1: $vipfloating" mailbody="`date '+%F %H:%M:%S'`: vrrptransition, `hostname` changed to be $1" echo $mailbody | mail -s"$mailsubject" $contact } case"$1" in master) notify master exit 0 ;; backup) notify backup exit 0 ;; fault) notify fault exit 0 ;; *) echo 'Usage: `basename $0`{master|backup|fault}' exit 1 ;; esac
进行测试
[root@node1keepalived]# ./notify.sh backup
[root@node1keepalived]# mail HeirloomMail version 12.4 7/29/08. Type ? forhelp. "/var/spool/mail/root":6 messages 1 new 6 unread U 1centos@stu2.magedu.c Sat Aug 1709:34 17/644 "*** SECURITY" U 2Cron Daemon Tue Aug 2700:01 22/747 "Cron <root@s" U 3Cron Daemon Fri Aug 3000:01 22/747 "Cron <root@s" U 4Mail Delivery System Fri Aug 3017:42 91/2751 "Undelivered " U 5Cron Daemon Tue Sep 3 00:01 22/747 "Cron<root@s" >N 6 root Thu Sep 26 21:19 18/700 "node1.magedu" &6 Message 6: Fromroot@node1.magedu.com Thu Sep 2621:19:32 2013 Return-Path:<root@node1.magedu.com> X-Original-To:root@localhost Delivered-To:root@localhost.magedu.com Date:Thu, 26 Sep 2013 21:19:32 +0800 To:root@localhost.magedu.com Subject:node1.magedu.com to be backup: 172.16.2.8 floating User-Agent:Heirloom mailx 12.4 7/29/08 Content-Type:text/plain; charset=us-ascii From:root@node1.magedu.com (root) Status:R 2013-09-26 21:19:32: vrrp transition, node1.magedu.com changed to bebackup &quit Held6 messages in /var/spool/mail/root Youhave mail in /var/spool/mail/root
通过传参数master|backup|fault验证都可以成功
在配置文件keepalived.conf中进行脚本调用
vrrp_instanceVI_1 {state MASTERinterface eth0virtual_router_id 51priority 100advert_int 1authentication {auth_type PASSauth_pass 1111}virtual_ipaddress {172.16.2.8} track_script { chk_maintainace } notify_master "/etc/keepalived/notify.shmaster" notify_backup"/etc/keepalived/notify.sh backup" notify_fault"/etc/keepalived/notify.sh fault" }
为node2提供同样的配置然后进行测试
[root@node1keepalived]# ls
down keepalived.conf keepalived.conf.bak notify.sh
[root@node1keepalived]# rm -f down
[root@node1keepalived]# mail
>N18 root Thu Sep 2621:57 18/700 "node1.magedu.comto be master: 172.16.2.8 floating"截取了一条
验证都可以成功
2、如何配置ipvs
virtual_server172.16.2.8 80{delay_loop 6lb_algo rrlb_kind NATnat_mask 255.255.0.0persistence_timeout 0protocol TCP
#real_server 172.16.2.1 80 {weight 1HTTP_GET {url { path / state_code 200 } connect_timeout 3 nb_get_retry 3 delay_before_retry 3 } } real_server 172.16.2.16 80 { weight 1 HTTP_GET { url { path / state_code 200 } connect_timeout 3 nb_get_retry 3 delay_before_retry 3 } } }
在node2上做同样的修改,启动httpd服务,keepalived能自动生成规则,然后查看ipvsadm规则
[root@node1keepalived]# ipvsadm -L -n
IPVirtual Server version 1.2.1 (size=4096) ProtLocalAddress:Port Scheduler Flags -> RemoteAddress:Port Forward Weight ActiveConn InActConn TCP 172.16.2.8:80 rr -> 172.16.2.1:80 Local 1 0 0 -> 172.16.2.16:80 Masq 1 0 0
3、如何对某特定服务做高可用?以nginx为例进行讲解
在两个节点上安装nginx
[root@node1~]# ansible all -m yum -a 'name=nginx state=present'
启动nginx服务,启动之前注意要停止httpd服务
[root@node1~]# ansible all -m shell -a 'service nginx start'
node2.magedu.com| success | rc=0 >> Startingnginx: [ OK ] node1.magedu.com| success | rc=0 >> Startingnginx: [ OK ]
对node1和node2中/etc/keepalived/下的notify.sh脚本进行修改
#!/bin/bash
#Author: MageEdu <linuxedu@foxmail.com>
#description: An example of notify script
#
vip=172.16.2.8 contact='root@localhost' notify(){ mailsubject="`hostname` to be $1: $vipfloating" mailbody="`date '+%F %H:%M:%S'`: vrrptransition, `hostname` changed to be $1" echo $mailbody | mail -s"$mailsubject" $contact } case"$1" in master) notify master /etc/rc.d/init.d/nginx start exit 0 ;; backup) notify backup /etc/rc.d/init.d/nginx stop exit 0 ;; fault) notify fault /etc/rc.d/init.d/nginx stop exit 0 ;; *) echo 'Usage: `basename $0`{master|backup|fault}' exit 1 ;; esac
然后启动keepalived服务,可以看到在node1上80端口开始启用
[root@node1keepalived]# ss -tanl | grep :80
LISTEN 0 128 *:80 *:*
然后在/etc/keepalive/下创建down文件,看nginx服务是否可以转移到node2上
[root@node1keepalived]# ls
keepalived.conf keepalived.conf.bak notify.sh
[root@node1keepalived]# touch down [root@node1keepalived]# ss -tanl | grep :80 [root@node1keepalived]# 在node2上进行查看 [root@node2keepalived]# ss -tanl | grep :80 LISTEN 0 128 *:80 *:*
验证成功,说明实现了nginx的高可用服务
总结:要对某特定服务做高可用有两个要点
一是:要提供监控服务脚本
二是:在vrrp实例中追踪服务
修改配置文件keepalived.conf
vrrp_script chk_nginx {script "killall -0 nginx"interval 1weight -2
}
vrrp_instanceVI_1 {state MASTERinterface eth0virtual_router_id 51priority 100advert_int 1authentication { auth_type PASS auth_pass 1111 } virtual_ipaddress { 172.16.2.8 } track_script { chk_maintainace chk_nginx }
在node2上做同样的修改
测试:
[root@node2keepalived]# killall nginx
Youhave new mail in /var/spool/mail/root
[root@node2keepalived]# ss -tanl | grep :80
[root@node2keepalived]#
在node1上
[root@node1keepalived]# ss -tanl | grep :80
LISTEN 0 128 *:80 *:*
验证成功
4、如何实现基于多虚拟路由的master/master模型?
要实现双主模型需要定义两个vrrp_instance,在node1的配置文件中要一下修改:
vrrp_instanceVI_1 {state MASTERinterface eth0virtual_router_id 51priority 100advert_int 1authentication {auth_type PASSauth_pass 1111}virtual_ipaddress {172.16.2.8} track_script { chk_maintainace chk_nginx } notify_master"/etc/keepalived/notify.sh master" notify_backup "/etc/keepalived/notify.shbackup" notify_fault "/etc/keepalived/notify.shfault" } vrrp_instance VI_2 { state BACKUP interface eth0 virtual_router_id 55 priority 99 advert_int 1 authentication { auth_type PASS auth_pass 2111 } virtual_ipaddress { 172.16.2.18 } track_script { chk_maintainace chk_nginx } notify_master"/etc/keepalived/notify.sh master" notify_backup"/etc/keepalived/notify.sh backup" notify_fault "/etc/keepalived/notify.shfault" }
在node2上做同样的修改,重启keepalived,进行测试
[root@node1keepalived]# service nginx status
nginx(pid 28688) is running... [root@node1keepalived]# ip addr show 1:lo: <LOOPBACK,UP,LOWER_UP> mtu 16436 qdisc noqueue state UNKNOWN link/loopback 00:00:00:00:00:00 brd00:00:00:00:00:00 inet 127.0.0.1/8 scope host lo inet6 ::1/128 scope host valid_lft forever preferred_lft forever 2:eth0: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc pfifo_fast stateUP qlen 1000 link/ether 00:0c:29:4e:22:fb brdff:ff:ff:ff:ff:ff inet 172.16.2.1/16 brd 172.16.255.255 scopeglobal eth0 inet 172.16.2.8/32 scopeglobal eth0 inet 172.16.10.8/16 brd 172.16.255.255scope global secondary eth0:0 inet6 fe80::20c:29ff:fe4e:22fb/64 scopelink valid_lft forever preferred_lft forever 3:pan0: <BROADCAST,MULTICAST> mtu 1500 qdisc noop state DOWN link/ether 6a:7a:4f:e0:c1:8a brdff:ff:ff:ff:ff:ff Youhave new mail in /var/spool/mail/root
在node2上
[root@node2keepalived]# service nginx start
Startingnginx: [ OK ] [root@node2keepalived]# ip addr show 1:lo: <LOOPBACK,UP,LOWER_UP> mtu 16436 qdisc noqueue state UNKNOWN link/loopback 00:00:00:00:00:00 brd 00:00:00:00:00:00 inet 127.0.0.1/8 scope host lo inet6 ::1/128 scope host valid_lft forever preferred_lft forever 2:eth0: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc pfifo_fast stateUP qlen 1000 link/ether 00:0c:29:74:c7:7b brd ff:ff:ff:ff:ff:ff inet 172.16.2.16/16 brd172.16.255.255 scope global eth0 inet 172.16.2.18/32 scopeglobal eth0 inet6 fe80::20c:29ff:fe74:c77b/64 scopelink valid_lft forever preferred_lft forever 3:pan0: <BROADCAST,MULTICAST> mtu 1500 qdisc noop state DOWN link/ether3a:4e:e8:4c:57:04 brd ff:ff:ff:ff:ff:ff 让node2的keepalived停掉,查看地址是否发生转移 [root@node1keepalived]# ip addr show 1:lo: <LOOPBACK,UP,LOWER_UP> mtu 16436 qdisc noqueue state UNKNOWN link/loopback 00:00:00:00:00:00 brd00:00:00:00:00:00 inet 127.0.0.1/8 scope host lo inet6 ::1/128 scope host valid_lft forever preferred_lft forever 2:eth0: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc pfifo_fast stateUP qlen 1000 link/ether 00:0c:29:4e:22:fb brd ff:ff:ff:ff:ff:ff inet 172.16.2.1/16 brd172.16.255.255 scope global eth0 inet 172.16.2.8/32 scopeglobal eth0 inet 172.16.2.18/32 scopeglobal eth0 inet 172.16.10.8/16 brd 172.16.255.255scope global secondary eth0:0 inet6 fe80::20c:29ff:fe4e:22fb/64 scopelink valid_lft forever preferred_lft forever 3:pan0: <BROADCAST,MULTICAST> mtu 1500 qdisc noop state DOWN link/ether 6a:7a:4f:e0:c1:8a brdff:ff:ff:ff:ff:ff Youhave new mail in /var/spool/mail/root
验证成功
转载于:https://www.cnblogs.com/dengbingbing/p/10327619.html
详解keepalived配置和使用相关推荐
- 详解keepalived配置
详解keepalived配置和使用 ! Configuration File for keepalivedglobal_defs { #指定keepalived在发生切换时需要发送email到的对象, ...
- mysql mybatis配置_mybatis详解 与配置mybatis+spring+mysql.doc
mybatis详解 与配置mybatis+spring+mysql.doc 还剩 30页未读, 继续阅读 下载文档到电脑,马上远离加班熬夜! 亲,很抱歉,此页已超出免费预览范围啦! 如果喜欢就下载吧, ...
- rsync的介绍及参数详解,配置步骤,工作模式介绍
rsync的介绍及参数详解,配置步骤,工作模式介绍 rsync是类unix系统下的数据镜像备份工具.它是快速增量备份.全量备份工具. Sync可以远程同步,支持本地复制,或者与其他SSH.rsync主 ...
- 企业网络分配项目,从连接到登陆,一步步来详解交换机配置
弱电几乎大部分的项目都跟网络有关,而所有的网络都离不开交换机的配置,很多朋友弱电项目做的比较困难,主要还是对网络技术不了解,尤其是交换的配置,那么今天我们以实例来讲解,企业网络分配项目,从连接到登陆, ...
- ElasticSearch预警服务-Watcher详解-Schedule配置
介绍 Watcher服务详解-定时器的设定 关于Schedule配置选择,Watcher提供了丰富的时间语法支持,采用UTC时间,来我们一起看下如何设置: 支持的设置方式: hourly:按小时周期设 ...
- 详解typora配置华为云图床
详解typora配置华为云图床 当前有很多不同的博客社区,不同的博客社区使用的编辑器也不尽相同,大概可以分为两种,一种是markdown格式,另外一种是富文本格式.例如华为云开发者社区文章编辑模式分为 ...
- MySQL主从同步详解与配置
https://zhuanlan.zhihu.com/p/335142300 MySQL主从同步详解与配置 第一部分[原理解析] * 应用背景* MySQL数据库自身提供的主从复制功能可以方便的实现数 ...
- 详解LVS配置DR模型
详解LVS配置DR模型 准备: 三台服务器,一台LVS,两台RS 操作 LVS: 8是随便写的 新配置一个虚拟网卡,作为LVS的VIP,之后的访问就用这个"192.168.28.150&qu ...
- Linux磁盘分区论文3000字,磁盘分区对齐详解与配置 – Linux篇
磁盘分区对齐详解与配置 – Linux篇 介绍 许多系统管理员可能不曾听过磁盘分区对齐之说,甚至一些有经验的存储管理员对分区对齐也不甚了解.磁盘分区不对齐现象是什么,为什么会造成比较严重的性能下降?相 ...
最新文章
- android bitmap 转drawable,android Drawable转换成Bitmap失败
- SAP MM 物料主数据consumption视图数据的更新?
- github入门必备概念
- Java开发学习--MongoDB
- 利用注入写Webshell(sql-lab第七关)
- ASP.NET MVC Action Filters
- css first-child,CSS :first-child 伪类
- R学习之——R用于文本挖掘(tm包)
- Vue入门 ---- vue-loader 、vue-cli
- 终于记住回车和换行cr lf的来由和含义了 -参考: http://www.cnblogs.com/me115/archive/2011/04/27/2030762.html...
- Ubuntu系统观看IPV6电视的方法详解
- HTML5期末大作业:美食网站设计——餐饮美食-咖啡(5页) HTML5网页设计成品_学生DW静态食品网页设计_web课程设计网页制作
- android用户中心头像选择功能的方法实现
- XJOI 1003 质因数分解
- 简谈计算机网络与网络编程
- ClearCase 介绍 1
- 地下水监测系统介绍 地下水水位在线监测系统解决方案及应用
- 那些年啊 那些事——一个程序员的奋斗史 ——105
- 为什么win32k.sys在System进程空间无法访问
- 使用Maven命令行快速创建项目骨架(archetype)