SVN create a new repository from another repository’s folder

I believe you're encountering a variant of the svndumpfilter: Invalid copy source path problem. This problem occurs when one of the directories/files included by svndumpfilter originally was copied (or, in your case, moved) from a section of the tree that is not being included. The original solution to this was Simon Tatham's svndumpfilter2 but his svn server seems to be down at the moment.

A slightly modified version is available here: http://www.dehora.net/hg/tools/raw-file/tip/svn/svndumpfilter2

Another variant here: http://furius.ca/pubcode/pub/conf/bin/svndumpfilter3.html

And another here: http://www.undersea.com/~nmb/svndumpfilter4

with explanation for svndumpfilter4 here (from archive.org - unfortunately the original is no longer accessible): http://replay.waybackmachine.org/20080827213200/http://www.undersea.com/~nburrell/blog/node/81

The variants are smart enough to use svnlook to retrieve the necessary source material even if it lives outside the included section of the tree.

Reading your original post and now this one, well, it sounds like you're really complicating things instead of using proven backup techniques as suggested by others. Specifically:

• Use the tools as they were meant to be be used: SVN for version control for your source files, rsync/amanda/bacula/whatever for your backups with a sensible backup window (5 minutes is not going to happen) like 12 hours or even better 24 hours.

• Backup to somewhere portable, like a USB drive you can grab in an emergency or better yet, off-site to a DropBox account for all your most important files (which is usually much less on disk than big binaries like movies, software ISOs, music, etc. that can usually be replaced/downloaded again at a later date).

• Use network drives (redirecting My Documents, setting up mapped drives from the Windows and Samba mounts from the Linux machines) and store your data on your new Linux file server with at least RAID1 configured. Put your money into good Intel GbE NICs and a decent GbE switch and you won't notice any ill effects of working over a network vs. locally (and with RAID1 disk mirroring, you're achieving the real-time sync you're looking for).

This is pretty much "File Server/backup 101" here, but what works for countless SOHO/small businesses should work for you.