之后会给你安装好Apache，MySQL，PHP。不过安装后一直无法访问，Apache提示500错误，这是个囧事……

此时可以使用irb –r rubygems来启动，则可解决

或者还有一种办法，在irb启动手，手动载入rubygems

<%= f.fields_for :attachments do |fields| %>
  <%= fields.file_field :uploaded_file %>
<% end %>

　　首先需要安装的就是CentOS Directory Server，使用yum命令轻松搞定

yum install centos-ds

　　安装完成之后，执行setup-ds.pl脚本来开始ds配置工作，配置过程按照提示一路下来还是比较简单的：

[root@ldap tmp]# setup-ds.pl

==============================================================================
This program will set up the CentOS Directory Server.

It is recommended that you have "root" privilege to set up the software.
Tips for using this  program:
  - Press "Enter" to choose the default and go to the next screen
  - Type "Control-B" or the word "back" then "Enter" to go back to the previous screen
  - Type "Control-C" to cancel the setup program

Would you like to continue with set up? [yes]:

==============================================================================
BY SETTING UP AND USING THIS SOFTWARE YOU ARE CONSENTING TO BE BOUND BY
AND ARE BECOMING A PARTY TO THE AGREEMENT FOUND IN THE
LICENSE.TXT FILE. IF YOU DO NOT AGREE TO ALL OF THE TERMS
OF THIS AGREEMENT, PLEASE DO NOT SET UP OR USE THIS SOFTWARE.

Do you agree to the license terms? [no]: yes

==============================================================================
Your system has been scanned for potential problems, missing patches,
etc.  The following output is a report of the items found that need to
be addressed before running this software in a production
environment.

CentOS Directory Server system tuning analysis version 10-AUGUST-2007.

NOTICE : System is i686-unknown-linux2.6.18-238.12.1.el5PAE (4 processors).

NOTICE : The net.ipv4.tcp_keepalive_time is set to 7200000 milliseconds
(120 minutes).  This may cause temporary server congestion from lost
client connections.

WARNING: There are only 1024 file descriptors (hard limit) available, which
limit the number of simultaneous connections. 

WARNING: There are only 1024 file descriptors (soft limit) available, which
limit the number of simultaneous connections. 

Would you like to continue? [no]: yes

==============================================================================
Choose a setup type:

   1. Express
       Allows you to quickly set up the servers using the most
       common options and pre-defined defaults. Useful for quick
       evaluation of the products.

   2. Typical
       Allows you to specify common defaults and options.

   3. Custom
       Allows you to specify more advanced options. This is
       recommended for experienced server administrators only.

To accept the default shown in brackets, press the Enter key.

Choose a setup type [2]:

==============================================================================
Enter the fully qualified domain name of the computer
on which you're setting up server software. Using the form
<hostname>.<domainname>
Example: eros.example.com.

To accept the default shown in brackets, press the Enter key.

Computer name [ldap..]: ldap
The hostname ldap does not look like a
fully qualified host and domain name.
If you feel you have made a mistake,
please go back to this dialog and enter another name.

==============================================================================
The server must run as a specific user in a specific group.
It is strongly recommended that this user should have no privileges
on the computer (i.e. a non-root user).  The setup procedure
will give this user/group some permissions in specific paths/files
to perform server-specific operations.

If you have not yet created a user and group for the server,
create this user and group using your native operating
system utilities.

System User [nobody]:
System Group [nobody]:

==============================================================================
The standard directory server network port number is 389.  However, if
you are not logged as the superuser, or port 389 is in use, the
default value will be a random unused port number greater than 1024.
If you want to use port 389, make sure that you are logged in as the
superuser, that port 389 is not in use.

Directory server network port [389]:

==============================================================================
Each instance of a directory server requires a unique identifier.
This identifier is used to name the various
instance specific files and directories in the file system,
as well as for other uses as a server instance identifier.

Directory server identifier [ldap]:

==============================================================================
The suffix is the root of your directory tree.  The suffix must be a valid DN.
It is recommended that you use the dc=domaincomponent suffix convention.
For example, if your domain is example.com,
you should use dc=example,dc=com for your suffix.
Setup will create this initial suffix for you,
but you may have more than one suffix.
Use the directory server utilities to create additional suffixes.

Suffix [dc=ldap]: o=neu

==============================================================================
Certain directory server operations require an administrative user.
This user is referred to as the Directory Manager and typically has a
bind Distinguished Name (DN) of cn=Directory Manager.
You will also be prompted for the password for this user.  The password must
be at least 8 characters long, and contain no spaces.
Press Control-B or type the word "back", then Enter to back up and start over.

Directory Manager DN [cn=Directory Manager]:
Password:
Password (confirm):
Your new DS instance 'ldap' was successfully created.
Exiting . . .
Log file is '/tmp/setuplkbF34.log'

[root@ldap tmp]#

　　至此，一个空的目录服务就配置完成，可以尝试下使用ldapsearch是否能搜到数据以确认目录服务是否正常启动：

ps aux | grep

ldapsearch -x -D "cn=Directory Manager" -W -b "o=neu"

　　随后可以使用导出的ldap数据开始进行迁移，如果你有自定义的schema可以存放在/etc/dirsrv/slapd-ldap/schema/目录下，按照数字编号编号好之后，系统就会自己载入了。

mv 98user.ldif /etc/dirsrv/slapd-ldap/schema/

　　使用ldif2db则可以将数据导入到CentOS Directory Server之中，不过一定要在离线情况下导入，否则会提示占用提示，此时只要将dirsrv服务停止即可：

service dirsrv stop

ns-slapd ldif2db -D /etc/dirsrv/slapd-ldap -s "o=neu" -i /tmp/neu.ldif

　　成功之后，重新启动dirsrv服务，再使用ldapsearch确认下数据是否倒进去了，至此大功告成！

dump database test to "/home/sybase/test.bak1" stripe on "/home/sybase/test.bak2"

　　同理，如果数据库大小超过4G，就需要分成3个备份文件了：

dump database test to "/home/sybase/test.bak1" stripe on "/home/sybase/test.bak2" stripe on "/home/sybase/test.bak3"

　　当然，就算数据库大小不到2G，愿意把他们分成多个文件也是支持的。

　　安装sybase需要两个rpm包，直接装上就可以。

　　安装成功之后，首先需要编辑/etc/init.d/sybase文件，在公共部分加入export LD_POINTER_GUARD=0，同时系统会自动生成一个sybase用户，还需要编辑该用户目录下的.profile文件，在合适的位置同样加入export LD_POINTER_GUARD=0。

　　编辑/etc/hosts文件，在合适位置加入sybase的主机名

　　在图形环境下用sybase用户登录系统，运行srvbuild，出现图形化安装界面，这部分相对简单，选上数据库服务器和备份服务器之后，其他相关参数按提示填写即可，不过输入框相当没人性，输错不能删除，只能用鼠标选中之后输入覆盖。

　　这部分流程结束之后，将会启动Sybase和Backup Server，使用isql登录一下，如果成功，则没有什么问题了。

　　测试很简单，通过PHP读写一定次数的APC与Memcache，并对他们所消耗的系统时间进行对比，由于是同一台机器上同程序的比较，所以消耗的时间只是参考值，曲线应该是类似的。具体过程就不赘述了，重点看结果：

测试数据1：APC不同Cache数量百万请求消耗时间

测试数据2：APC保存不同Cache数量消耗时间

测试数据3：Memcache不同Cache数量10W请求消耗时间

　　测试结果很容易看出来，当Cache数量巨大的时候，APC的时间消耗为O(N)，而Memcache的时间消耗为O(1)，虽然APC为共享内存，访问速度快，但是一旦APC的Cache数量过大，遍历所产生的时间消耗要大于Memcache中间层所产生的时间消耗，就会出现APC的性能不如Memcache的效果。

　　刚开始以为要实现这个功能很复杂，看了下代码之后发现在StatusNet中直接有一个配置开关可以直接修改，直接在config.php中加一句话：

$config['singleuser']['enabled'] = true;

　　StatusNet是不是非常地好用、方便呢，快一起来搭建吧！

addPlugin('GoogleAnalytics', array(
    'code' => 'UA-440814-12'
));

　　然后就可以保存退出，StatusNet会根据你的配置信息，自动在页面需要的位置加上GoogleAnalytics的，等上几个小时，你就可以在你的GoogleAnalytics帐户中看到StatusNet相关统计了！