我试图在居住在Vagrant上的CentOS上安装mongodb。 Mongo已安装，但是当我尝试安装mongodb时会出现一些错误，以下是行为：
[root@localhost vagrant]# pecl install mongodb
PHP Warning: Module 'dom' already loaded in Unknown on line 0
downloading mongodb-1.2.9.tgz ...
Starting to download mongodb-1.2.9.tgz (786,049 bytes)
..............................................................done:
786,049 bytes
could not extract the package.xml file from
"/tmp/pear/download/mongodb-1.2.9.tgz"
Download of "pecl/mongodb" succeeded, but it is not a valid package
archive
Error: cannot download "pecl/mongodb"
Download failed
install failed
[root@localhost vagrant]#
在不同链接上尝试了几个小时之后，我终于来了。请说明出了什么问题。