Creating and Verifying a Reliable backup

Hello,
We are very paranoid about our Subversion repo, notwithstanding the fact
that the previous sysadmin didn't back it up. But that's another story. Now
I'm here at my job, I've inherited the repo admin duties, and I want to
back it up reliably. If we lose it, we're all out of work.

My question is: How do I back it up reliably, and verify it so that I can
deliver a 100% recovery guarantee to my boss? I have Subversion 1.8.4 on a
CentOS 6.3 server, and Tortoise SVN 1.8.11 on Windows 7 clients.

I am thinking to do both an svn hotcopy to one directory, and an rsync to
another. The svn hotcopy will give me a backup that I'm pretty sure is
reliable (see Notes below). Assuming httpd is down and I can guarantee that
I am the only person who will be logged into the SVN server, can I expect
with 99.9% surety that the svn repos are quiescent?

Thanks.

-- 
-Mike Schwager
Notes:
We're a little worried about svn hotcopy; we ran into a bug that came about
under 1.8 when working with older repos; the hotcopy exits with the
following error:
svnadmin: E200002: Serialized hash missing terminator
I have compiled subversion-1.9.4 on the server under /opt/subversion-1.9.4.
If I run that version of svn hotcopy, it appears to work and svnverify
exits successfully. But if I look at all the files under both the original
and the hotcopy on one of our repos, I find that a file is
missing: repos2/db/rev-prop-atomics.shm . That's probably ok, but still-
how do we know the latest hotcopy, and hotcopies of the future, are and
will remain 100% bug-free?