svnsync

From: http://svn.collab.net/repos/svn/trunk/notes/svnsync.txt

                        ==== What Is It? ====

svnsync is a tool for creating and maintaining read-only mirrors of
subversion repositories.  It works by replaying commits that occurred
in one repository and committing it into another.

                        ==== Basic Setup ====

First, you need to create your destination repository:

$ svnadmin create dest

Because svnsync uses revprops to keep track of bookkeeping information
(and because it copies revprops from the source to the destination)
it needs to be able to change revprops on your destination repository.
To do this you'll need to set up a pre-revprop-change hook script that
lets the user you'll run svnsync as make arbitrary propchanges.

$ cat <<'EOF' > dest/hooks/pre-revprop-change
#!/bin/sh
USER="$3"

if [ "$USER" = "svnsync" ]; then exit 0; fi

echo "Only the svnsync user can change revprops" >&2
exit 1
EOF
$ chmod +x dest/hooks/pre-revprop-change

$ svnsync init --username svnsync file://`pwd`/dest \
 http://svn.example.org/source/repos
Copied properties for revision 0
$

Note that the arguments to 'svnsync init' are two arbitrary repository
URLs.  The first is the destination, which must be empty, and the second
is the source.

Now you can just run the 'svnsync sync' command to synchronize pending
revisions.  This will copy any revisions that exist in the source repos
but don't exist in the destination repos.

$ svnsync sync file://`pwd`/dest
Committed revision 1.
Copied properties for revision 1.
Committed revision 2.
Copied properties for revision 2.
Committed revision 3.
Copied properties for revision 3.
...

                           ==== Locks ====

If you kill a sync while it's occurring there's a chance that it might
leave the repository "locked".  svnsync ensures that only one svnsync
process is copying data into a given destination repository at a time
by creating a svn:sync-lock revprop on revision zero of the destination
repository.  If that property is there, but you're sure no svnsync is
actually running, you can unlock the repository by deleting that revprop.

$ svn pdel --revprop -r 0 svn:sync-lock file://`pwd`/dest

                            ==== FAQ ====

Q: So what can I do with this thing anyway?

A: Well, anything that's read-only.  As long as you don't commit changes
to the destination repository you're all set.  This means destination
repositories are good for providing offsite mirrors, read-only mirrors,
etc.

Q: What if I want to check out from a mirror, but commit to the master?

A: That's possible, but requires some gymnastics.  You see, each repository
has its own UUID, which is stored in the working copy, so if you check
out from the mirror, and then do a 'svn switch --relocate' to point to
the master it'll error out.  To make this work you need to make sure that
the mirrors have the same UUID as the master.  You can set a repository
UUID via the following technique:

$ cat - <