You have to make sure of two things:
1. If you have open_basedir restrictions in your php.ini file you must put the NFS root path in there, otherwise PHP will be unable to access this directory.
2. Mind your ownership. NFS shares use the ownership (user, group) numerical IDs of the remote system. In order to make the directory writable, you may have to give the target directory in your NFS share 0777 permissions.
3. If you are using PHP in CGI/FastCGI mode running in a chroot jail, please note that the effective filesystem root is your site's root directory. This means that any directory outside your site's root is inaccessible, as it is outside the chroot jail PHP is confined in. Using a symlink to the NFS share also won't work, as the symlink points to a non-existent path when you are inside the chroot jail. Under these circumstances, the only way to deal with the issue is to remove the chroot jail and use a different security method, e.g. suPHP and/or open_basedir restrictions.
Nicholas K. Dionysopoulos
Lead Developer and Director
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