IT 技术领域学海无涯。其实任何领域都学海无涯，无非 IT 发展太快了，让我有更多嘘唏。希望我掌握的技术有如小小草，虽然渺小，却有旺盛的生命力。
wget http://www.magentocommerce.com/downloads/assets/1.3.2.3/magento-1.3.2.3.tar.gz
If you download Magento from the download page, you see this link http://www.magentocommerce.com/getmagento/1.3.2.3/magento-1.3.2.3.tar.gz. But you can not use wget http://www.magentocommerce.com/getmagento/1.3.2.3/magento-1.3.2.3.tar.gz without specifying referrer. Some technique of anti hot link is implemented there.
netstat -nap | grep 8080
When using phpmyadmin, after select a database, then click on Privileges, you might run into a error saying
Unknown column ‘Event_priv’ in ‘field list’
The error will go after you run
mysql_upgrade
in command line.
I feel mysql query speed is improved after running “mysql_update”.
Connection speed of the Godaddy server is generally slower than the 1&1 server. It was test proven from Europe and China. However, when connecting to downloads.sourceforge.net, Godaddy is faster.
The Godaddy server automatically chooses the mirror site softlayer.dl.sourceforge.net, and the average speed is 8.55M/s. The 1&1 server chooses dfn.dl.sourceforge.net, and the speed is 70K/s. When I force the 1&1 server to download from softlayer.dl.sourceforge.net, the speed does not improve. It is slower even than I download from my PC via ADSL.
I do not know why there is such a big difference in connection speed from different locations.
Follow these 3 steps to gracefully stop and start Nginx without losing any queries. It works like a charm.
nginx -tps -ef | grep "nginx: master process" | grep -v "grep" | awk -F ' ' '{print $2}' kill -HUP ????Occasionally I need to open .ai (Adobe Illustrator) and .cdr (Coreldraw) files on Fedora, and I found Inkscape is good enough for me. I won’t edit these files so I don’t know Inkscape full capacity.
非常典型的多层架构：
第一层 Nginx
第二层 php fastcgi
第三层 memcached
第四层 MySql
Apache 有个 mod_php，相当于合并了第一层和第二层，Nginx 没有 module for php，这不是什么问题，分层更利于扩展。第三层的加入完全是为了减轻数据库压力，提高性能。目前第2，3，4层之间的优化差不多到极限了（或者说到我能力的极限了），但第1，2层之间尚有潜力可挖。
not_in_use.php 和 not_in_use.html 都是一个静态文件，没有数据库操作。但 php 文件必须由 Nginx 经由 php fastcgi （使用 unix socket）产生，html 则由 Nginx 直接访问文件系统，就单因素分析，php fastcgi 是普通文件系统速度的34%，所以要想办法绕开 php fastcgi。以下测试在数据中心主机上直接运行 ApacheBench。
测试一：
$ ab -kc 100 -n 500 http://magento/not_in_use.php
This is ApacheBench, Version 2.0.40-dev <$Revision: 1.146 $> apache-2.0
Copyright 1996 Adam Twiss, Zeus Technology Ltd, http://www.zeustech.net/
Copyright 2006 The Apache Software Foundation, http://www.apache.org/
Benchmarking magento (be patient)
Completed 100 requests
Completed 200 requests
Completed 300 requests
Completed 400 requests
Finished 500 requests
Server Software: nginx/0.6.36
Server Hostname: magento
Server Port: 80
Document Path: /not_in_use.php
Document Length: 7686 bytes
Concurrency Level: 100
Time taken for tests: 0.336355 seconds
Complete requests: 500
Failed requests: 0
Write errors: 0
Keep-Alive requests: 0
Total transferred: 4089329 bytes
HTML transferred: 4004406 bytes
Requests per second: 1486.52 [#/sec] (mean)
Time per request: 67.271 [ms] (mean)
Time per request: 0.673 [ms] (mean, across all concurrent requests)
Transfer rate: 11871.39 [Kbytes/sec] received
Connection Times (ms)
min mean[+/-sd] median max
Connect: 0 11 17.8 3 58
Processing: 13 49 17.9 50 94
Waiting: 3 45 18.8 46 88
Total: 25 60 14.2 61 94
Percentage of the requests served within a certain time (ms)
50% 61
66% 70
75% 72
80% 74
90% 79
95% 80
98% 84
99% 86
100% 94 (longest request)
=======================================================
测试二：
$ ab -kc 100 -n 500 http://magento/not_in_use.html
This is ApacheBench, Version 2.0.40-dev <$Revision: 1.146 $> apache-2.0
Copyright 1996 Adam Twiss, Zeus Technology Ltd, http://www.zeustech.net/
Copyright 2006 The Apache Software Foundation, http://www.apache.org/
Benchmarking magento (be patient)
Completed 100 requests
Completed 200 requests
Completed 300 requests
Completed 400 requests
Finished 500 requests
Server Software: nginx/0.6.36
Server Hostname: magento
Server Port: 80
Document Path: /not_in_use.html
Document Length: 7686 bytes
Concurrency Level: 100
Time taken for tests: 0.115725 seconds
Complete requests: 500
Failed requests: 0
Write errors: 0
Keep-Alive requests: 500
Total transferred: 3959000 bytes
HTML transferred: 3843000 bytes
Requests per second: 4320.59 [#/sec] (mean)
Time per request: 23.145 [ms] (mean)
Time per request: 0.231 [ms] (mean, across all concurrent requests)
Transfer rate: 33406.78 [Kbytes/sec] received
Connection Times (ms)
min mean[+/-sd] median max
Connect: 0 3 7.3 0 22
Processing: 7 17 4.1 18 23
Waiting: 7 16 4.0 17 23
Total: 7 20 9.9 18 41
Percentage of the requests served within a certain time (ms)
50% 18
66% 20
75% 22
80% 37
90% 39
95% 40
98% 41
99% 41
100% 41 (longest request)
今天 Fedora 的一个更新后提示我 logout and relogin，结果我 logout 后死机。重启，进度条到100%后还是死机。
幸好我注意到这个更新是关于 ntfs 的，马上把 /etc/fstab 里我添加的几个条目注释掉，系统又可以启动了。我再细察了/etc/fstab，关于 cifs 的加载，原先写得不是很规范，缺少 sec=none 参数，造成 Fedora 更新后不能启动。
为了让 Opentaps 在系统启动后自动启动，我在 /etc/rc.d/rc.local 里添了一行
/path/to/opentaps/startofbiz.sh
在 Opentaps 1.0.4 版之前用这个方法启动 Opentaps 没发现大的问题，但 1.0.4 版运行 startofbiz.sh 的当前目录必须为 opentaps 的目录，不能再用上述办法启用 Opentaps。再说上述办法并不是正统的以 service 运行 Opentaps，所以我又重新寻找一个能让 Opentaps 自启动的办法。其实也很简单：
cp /path/to/opentaps/rc.ofbiz /etc/init.d/ofbizchmod 755 /etc/init.d/ofbizchkconfig --add ofbizchkconfig --level 235 ofbiz onservice ofbiz startParallels Plesk 对我来说是鸡肋。1＆1 送了这玩意一年的许用证，一年以后我还用 1＆1 吗？我如果用了 Parallels Plesk 就怕象吃鸦片上瘾，以后如果离开 1＆1，别人家如果不送 Parallels Plesk 就要花钱买，那时我会觉得很懊恼。
1&1 既然送了 Parallels Plesk，我也在 Parallels Plesk Panel 里转了一圈，觉得它算是一款好的商业软件，只不过不对我的胃口罢了。正因为如此，我没删 Parallels Plesk，只是将 psa service 停止了。
如此相安无事过了几个星期，今天突然发现 opentaps 不能启动了。一查，8443 端口被占用了，我马上想到是 Parallels Plesk 又复活了，难道 psa 还有一个守护进程？Parallels Plesk 这么设计大概为了保证 Panel 的 up time，但有点病毒作风，再加我也搞不清它的机理，看来要把它删了一了百了。