making an independent copy of svn repository

Try svnadmin hotcopy. You can look it up in the repo maintenance section of the svn book (Version Control with Subversion), specifically in the section "repository replication". There is also the svnsync command, but you only need this if you're trying to create a mirror.

To quote the book: "simply doing a recursive directory copy runs the risk of generating a faulty backup. In the case of Berkeley DB, the documentation describes a certain order in which database files can be copied that will guarantee a valid backup copy. A similar ordering exists for FSFS data." FSFS and Berkeley DB are the two database options that normal subversion installations provide, and FSFS is the default.

Example usage (again from book):

$ svnadmin hotcopy /var/svn/repos /var/svn/repos-backup

Use svnrdump tool to get repository dump (complete revision history) over HTTPS and svn:// (i.e. remotely) and svnadmin load it into a new clean repository. Note that in order to get the complete repository dump you must have full Read access to all trees in the repository, otherwise the dump can be incomplete.