Best way to create an SVN-Mirror?
Solution 1:
You could try an approach similar to the one we use at Atlassian
https://www.atlassian.com/blog/archives/subversion_replication_at_atla?_ga=2.217251286.1933127788.1517539727-1159165484.1517539727
disclaimer: I am currently an Atlassian employee, but was not involved in implementing this solution (only maintaining it)
As I said above in the comment, svnsync, run from a remote repository behaves deterministically. It cannot apply changesets out of order. So the only problem you have using a remote repository is the amount of lag due to changeset propagation.