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Dec 27
Blocked time includes any pre-processing time (such as cache lookup) and the time spent waiting for a network connection to become available. Internet Explorer will only create a maximum of two concurrent network connections per host name (i.e. www.microsoft.com) and will queue up requests until a network connection is available. Often the Blocked time is the most significant factor in the download time of images embedded in a web page.

闭塞时间,包括所有的过程之前的时间(像,cache对比)和等待网络链接的时间,IE在每个主机名(像www.microsoft.com)下最多只创建两个当前的网络连接,而且要排队等待直到这个网络链接可用,通常,闭塞时间影响网页中图片加载时间的重要因素。

Connect is the time required to create a TCP connection to the web server (or proxy). If a secure HTTPS connection is being used this time includes the SSL handshake process. Keep-Alive connections are often used to avoid the overhead of repeatedly connecting to the web server.

连接时间,是创建TCP连接到服务器或者代理服务器所花费的时间,如果一个包含SSL的安全的HTTPS连接存在,Keep-Alive链接经常被用到,以避免多次重复的连接WEB服务器。

Send is the time required to send the HTTP request message to the server and will depend on the amount of data that is sent to the server. For example, long Send times will result from uploading files using an HTTP POST

发送,是发送HTTP请求到服务器的时间,而且这个时间取决与发送请求的数据量的大小,例如,长的发送时间是由于用PSOT方式上传文件造成的。

Wait is the idle time spent waiting for a response message from the server. This value includes delays introduced due to network latency and the time required to process the request on the web server.

等待,是花费在等待服务器响应消息的空闲时间,这个值包括网络延迟和服务器处理请求的时间。

Receive is the time taken to read the response message from the server. This value will be depend on the size of the content returned, network bandwidth and whether HTTP compression was used.

接收,是花费在从服务器读取响应消息的时间。这个值可以受到请求消息内容的大小,网络带宽和是否使用了HTTP压缩。

Cache Read is the time taken to read the content from the browser cache during (Cache) or 304 responses.

缓存读取,是花费在从浏览器缓存中读取内容或者304响应的时间。

TTFB (or Time To First Byte) is the duration from the initial network request being initiated by the browser to the first byte being received from the server. It includes TCP connection time, the time to send the request and the time taken to get the first byte of the response message.

TTFB,是最初的网络请求被发起到从服务器接收到第一个字节这段时间,它包含了TCP连接时间,发送HTTP请求时间和获得响应消息第一个字节的时间。

Network is the total duration of all network related operations for an HTTP request.

Network,是所有的对一个HTTP请求的相关操作的这段时间。
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Dec 5
此脚本用于新装Linux的相关配置工作,比如禁掉iptable和SElinux及ipv6,优化系统内核,停掉一些没必要启动的系统服务等。此脚本尤其适全大批新安装的Centsos系列的服务器,脚本代码如下所示(此脚本在Centos5.5_x64下已通过):
#!/bin/bash
# Created by kerryhu
# MAIL:king_819@163.com
# BLOG:http://kerry.blog.51cto.com
cat << EOF
+--------------------------------------------------------------+
|         === Welcome to Centos System init ===                |
+--------------------------------------------------------------+
+--------------------------by kerry----------------------------+
EOF

#set ntp
yum -y install ntp
echo "* 3 * * * /usr/sbin/ntpdate 210.72.145.44 > /dev/null 2>&1" >> /etc/crontab
service crond restart
#set ulimit
echo "ulimit -SHn 102400" >> /etc/rc.local
#set locale
#true > /etc/sysconfig/i18n
#cat >>/etc/sysconfig/i18n<<EOF
#LANG="zh_CN.GB18030"
#SUPPORTED="zh_CN.GB18030:zh_CN:zh:en_US.UTF-8:en_US:en"
#SYSFONT="latarcyrheb-sun16"
#EOF
#set sysctl
true > /etc/sysctl.conf
cat >> /etc/sysctl.conf << EOF
net.ipv4.ip_forward = 0
net.ipv4.conf.default.rp_filter = 1
net.ipv4.conf.default.accept_source_route = 0
kernel.sysrq = 0
kernel.core_uses_pid = 1
net.ipv4.tcp_syncookies = 1
kernel.msgmnb = 65536
kernel.msgmax = 65536
kernel.shmmax = 68719476736
kernel.shmall = 4294967296
net.ipv4.tcp_max_tw_buckets = 6000
net.ipv4.tcp_sack = 1
net.ipv4.tcp_window_scaling = 1
net.ipv4.tcp_rmem = 4096 87380 4194304
net.ipv4.tcp_wmem = 4096 16384 4194304
net.core.wmem_default = 8388608
net.core.rmem_default = 8388608
net.core.rmem_max = 16777216
net.core.wmem_max = 16777216
net.core.netdev_max_backlog = 262144
net.core.somaxconn = 262144
net.ipv4.tcp_max_orphans = 3276800
net.ipv4.tcp_max_syn_backlog = 262144
net.ipv4.tcp_timestamps = 0
net.ipv4.tcp_synack_retries = 1
net.ipv4.tcp_syn_retries = 1
net.ipv4.tcp_tw_recycle = 1
net.ipv4.tcp_tw_reuse = 1
net.ipv4.tcp_mem = 94500000 915000000 927000000
net.ipv4.tcp_fin_timeout = 1
net.ipv4.tcp_keepalive_time = 1200
net.ipv4.ip_local_port_range = 1024 65535
EOF
/sbin/sysctl -p
echo "sysctl set OK!!"
#close ctrl+alt+del
sed -i "s/ca::ctrlaltdel:\/sbin\/shutdown -t3 -r now/#ca::ctrlaltdel:\/sbin\/shutdown -t3 -r now/" /etc/inittab
#set purview
chmod 600 /etc/passwd
chmod 600 /etc/shadow
chmod 600 /etc/group
chmod 600 /etc/gshadow
#disable ipv6
cat << EOF
+--------------------------------------------------------------+
|         === Welcome to Disable IPV6 ===                      |
+--------------------------------------------------------------+
EOF
echo "alias net-pf-10 off" >> /etc/modprobe.conf
echo "alias ipv6 off" >> /etc/modprobe.conf
/sbin/chkconfig --level 35 ip6tables off
echo "ipv6 is disabled!"
#disable selinux
sed -i '/SELINUX/s/enforcing/disabled/' /etc/selinux/config
echo "selinux is disabled,you must reboot!"
#vim
sed -i "8 s/^/alias vi='vim'/" /root/.bashrc
echo 'syntax on' > /root/.vimrc
#zh_cn
sed -i -e 's/^LANG=.*/LANG="en"/'   /etc/sysconfig/i18n
#init_ssh
ssh_cf="/etc/ssh/sshd_config"
sed -i -e '74 s/^/#/' -i -e '76 s/^/#/' $ssh_cf
#sed -i "s/#Port 22/Port 65535/" $ssh_cf
sed -i "s/#UseDNS yes/UseDNS no/" $ssh_cf
#client
sed -i -e '44 s/^/#/' -i -e '48 s/^/#/' $ssh_cf
service sshd restart
echo "ssh is init is ok.............."
#chkser
#tunoff services
#--------------------------------------------------------------------------------
cat << EOF
+--------------------------------------------------------------+
|         === Welcome to Tunoff services ===                   |
+--------------------------------------------------------------+
EOF
#---------------------------------------------------------------------------------
for i in `ls /etc/rc3.d/S*`
do
              CURSRV=`echo $i|cut -c 15-`
echo $CURSRV
case $CURSRV in
          crond | irqbalance | microcode_ctl | network | random | sshd | syslog | local )
      echo "Base services, Skip!"
      ;;
      *)
          echo "change $CURSRV to off"
          chkconfig --level 235 $CURSRV off
          service $CURSRV stop
      ;;
esac
done
echo "service is init is ok.............."

本脚本摘录自《构建高可用Linux服务器》(机械工业出版社) 一书,转载麻烦注明出处,谢谢。
Nov 19
在dell的11代服务器内存模式有三种,Memory Optimized Mode、Advanced ECC Mode、Mirror Mode。这三种有什么区别呢?


Memory Optimized Mode:

DDR3的内存控制器都在CPU上,每个CPU上有三个独立的Memory Controller Hub(MCH)。在这个模式下,MCHs是独立工作的,一个可以读,一个可以写,一个可以空闲。内存可以安装在one、two、three  chanels上。这也就意味着有些不符合常规的内存接法可以正常工作。比如3G,6G,12G。

Advanced ECC Mode:

这个模式下,将两个MCH绑在一起变成一个128位的总线,另外一个MCH无法使用,如果开启这个模式并在剩余的MCH上接内存,机器就会报错。

Mirror Mode:

这个模式下,系统应用三个chanel中的两个,每个chanel写同样的数据,读的时候采取轮询的方式。如果发现有一个chanel的内存出错,系统会自动屏蔽此chanel。运用这种模式,能使用的内存容量是安装上去的一半。

假设有9个dimm,一共有三个chanel,A1A4A7 一个chanel,A2A5A8一个chanel,A3A6A9一个chanel.而Advanced ECC Mode 和Mirror Mode只能用到两个MCH,也就是只能使用两个chanel,默认是将A1A4A7这个chanel闲置。

总结:如果每个CPU的内存条数为1,3,9就只能使用Memory Optimized模式,2,4,6条数的都建议使用Advanced ECC模式。Mirror排除在外。

如图:
点击在新窗口中浏览此图片
点击在新窗口中浏览此图片
参考资料:
http://www.dell.com/downloads/global/products/pedge/en/ddr3_white_paper_r410_en.pdf
http://www.dell.com/downloads/global/products/pedge/en/server-pedge-installing-upgrading-memory-11g.pdf
Nov 15
之前倒没有注意这个问题,今天在安装一个bo-blog博客系统的时候,输入了MYSQL的信息和管理员信息之后出现数据库报错,TYPE=MyISAM在MYSQL5.5.X已经被ENGINE=MyISAM取代了,并且不兼容之前的TYPE=MyISAM。

解决办法就是:
进入bo-blog的安装目录install下,使用Dreamweaver 或其他网页开发工具编辑install.php文件,注意不要使用windows自带的记事本编辑,有可能会有问题,打开文件之后将该文件内的所有:

“TYPE=MyISAM”
修改为:
“ENGINE = MYISAM”


“TYPE = MyISAM”
修改为:
“ENGINE = MYISAM”

注意:最终都是修改为“ENGINE = MYISAM”(‘=’号两边各有一个空格),用批量替换就可以。保存之后上传替换掉之前的install.php,就可以继续进行安装了。
Oct 11
查看cacti的日志:
Log File [Total Lines: 14 - All Items Shown]
09/18/2012 09:50:49 AM - AUTH LOGIN: User 'admin' Authenticated
09/18/2012 09:50:16 AM - MANAGE: Poller[0] Checking Manage
09/18/2012 09:50:06 AM - SYSTEM SYSLOG STATS:Time:0.28 Deletes:0 Incoming:0 Removes:0 XFers:39 Alerts:0 Alarms:0 Reports:0
09/18/2012 09:50:06 AM - SYSTEM THOLD STATS: Time:0.0172 Tholds:0 DownHosts:0
09/18/2012 09:50:06 AM - SYSTEM STATS: Time:-28796.2396 Method:spine Processes:1 Threads:1 Hosts:2 HostsPerProcess:2 DataSources:15 RRDsProcessed:15
09/18/2012 05:45:16 PM - MANAGE: Poller[0] Checking Manage
09/18/2012 05:45:10 PM - RECACHE STATS: RecacheTime:4.3342 HostsRecached:1
09/18/2012 05:45:06 PM - SYSTEM SYSLOG STATS:Time:0.55 Deletes:0 Incoming:0 Removes:0 XFers:30 Alerts:0 Alarms:0 Reports:0
09/18/2012 05:45:06 PM - PCOMMAND: Poller[0] Host[1] WARNING: Recache Event Detected for Host
09/18/2012 05:45:05 PM - SYSTEM THOLD STATS: Time:0.0343 Tholds:0 DownHosts:0
09/18/2012 05:45:05 PM - SYSTEM STATS: Time:2.6126 Method:spine Processes:1 Threads:1 Hosts:2 HostsPerProcess:2 DataSources:15 RRDsProcessed:15
09/18/2012 05:45:02 PM - POLLER: Poller[0] WARNING: Cron is out of sync with the Poller Interval! The Poller Interval is '300' seconds, with a maximum of a '300' second Cron, but 1296601 seconds have passed since the last poll!

可以看出刚开始时间是下午5:45,最后又变成早上9:50,时间是先超前最后又变成正确的了(这是由于系统每过10分钟会和时间服务器同步一次时间)。
这样会导致数据库记录poller的执行时间出问题:
mysql> select * from poller_time
    -> ;
+----+------+-----------+---------------------+---------------------+
| id | pid  | poller_id | start_time          | end_time            |
+----+------+-----------+---------------------+---------------------+
|  1 | 2231 |         0 | 2012-09-18 17:50:03 | 2012-09-18 09:50:05 |
+----+------+-----------+---------------------+---------------------+
1 row in set (0.00 sec)

mysql>
可以看出poller的执行结束时间end_time比开始时间start_time更早,这样会导致poller进程停止工作,直到系统时间超过了start_time,poller进程才回开始工作,图像才能出来!这里要特别说明下:不能简单地修改数据库poller_time表里的时间,因为数据库里面还有好多表也记录了采集各种数据的时间。
所以解决办法有两个:
1 等系统时间超过start_time(过了下午5点50),一切恢复正常(如果你有耐心 )。
2 如果现在系统的时间不正确先把系统时间修改正确,然后删除/var/www/html/rra/下面的所有文件,最后强制执行poller程序重新生成/var/www/html/rra/下面的所有文件。操作过程如下:
# rm -rf /var/www/html/rra/*
# /usr/bin/php /var/www/html/poller.php --force
Manage : initializing...
Checking Manage... TCP :
      Data Source : 9 is : 1
Checking Manage... TCP :
      Data Source : 8 is : 1
OK u:0.00 s:0.01 r:1.87
OK u:0.00 s:0.01 r:1.87
OK u:0.00 s:0.02 r:1.88
OK u:0.00 s:0.02 r:1.88
OK u:0.00 s:0.02 r:1.90
OK u:0.00 s:0.02 r:1.90
OK u:0.00 s:0.02 r:1.91
OK u:0.00 s:0.02 r:1.91
OK u:0.00 s:0.02 r:1.92
OK u:0.00 s:0.02 r:1.92
OK u:0.00 s:0.02 r:1.93
OK u:0.00 s:0.02 r:1.93
OK u:0.00 s:0.02 r:1.95
OK u:0.00 s:0.02 r:1.95
OK u:0.00 s:0.02 r:1.96
OK u:0.00 s:0.02 r:1.96
OK u:0.00 s:0.02 r:1.97
OK u:0.00 s:0.02 r:1.97
OK u:0.00 s:0.02 r:1.98
OK u:0.00 s:0.02 r:1.98
OK u:0.00 s:0.02 r:1.99
OK u:0.00 s:0.02 r:1.99
OK u:0.00 s:0.03 r:2.00
OK u:0.00 s:0.03 r:2.01
OK u:0.00 s:0.03 r:2.02
OK u:0.00 s:0.03 r:2.02
OK u:0.00 s:0.03 r:2.03
OK u:0.00 s:0.03 r:2.03
OK u:0.00 s:0.03 r:2.05
OK u:0.00 s:0.03 r:2.05
09/18/2012 11:38:00 AM - SYSTEM STATS: Time:2.2115 Method:spine Processes:1 Threads:1 Hosts:2 HostsPerProcess:2 DataSources:15 RRDsProcessed:15
#
注意一定要先删除/var/www/html/rra/下的所有文件在执行/usr/bin/php /var/www/html/poller.php --force,过一会看看是不是出图了。
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