You’ve configured open_basedir correctly to allow access to /usr/share/pear but to call the file correctly you can either call DB.php using the absolute path

/usr/share/pear/DB.php

or if you want to just use DB.php you will also need to modify include_path to use

/usr/share/pear

You can just include, include_path to the vhost where you added open_basedir. Something like

php_admin_value include_path “/usr/share/pear”

then run

/usr/local/psa/admin/sbin/websrvmng –reconfigure-vhost –vhost-name=domain.com
Here are step by step instructions, on how to add an include path for your (dv) Dedicated Virtual 3.5 Extreme.

http://kb.mediatemple.net/questions/514/(dv)+HOWTO%3A+Enable+PEAR%7B47%7DSet+open_basedir+and+include_path.

Also, you may need to modify your php.ini file.

Configuring the php.ini file on a DV requires the following.

1. Access to an SSH client.
(http://kb.mediatemple.net/article.php?id=016)
2. Basic knowledge of SSH commands
(http://kb.mediatemple.net/article.php?id=247)
3. And the root password.  Root access can easily be enabled using our Root Access and Developer Tools function in the Admin Section of the AccountCenter.

The most common parameters changed in the php.ini file are:

safe_mode
register_globals
max_upload_filesize
post_max_size
max_execution_time

Use the following command at the command prompt to start editing:

vi /etc/php.ini

If you are looking for a specific parameter and would like to go
straight there, type the following:

vi +/parameter /etc/php.ini

example: vi +/safe_mode /etc/php.ini

For more information on using the vi command, review kb article

http://kb.mediatemple.net/article.php?id=247