SubGit is a tool that is used for SVN to Git Migration. It is developed by a company called TMate. It converts the SVN repositories to Git and lets you do work on both the systems concurrently. It auto-syncs the SVN with Git.
You can create an SVN||Git mirror using this tool. SubGit should be installed on your Git server. It will detect all the settings of your remote SVN repository, including SVN revisions, branches, and tags, and converts them into Git commits.
It also preserves the history including tracking merge data.