'svnadmin hotcopy' follows the standard recommended BDB hot-backup procedure:
1. copy all repository files somewhere else.
2. recopy just the logfiles.
3. run recovery on the backup.
The problem is that if you're using BDB 4.2 with the auto-logfile-removal option
turned on (which is the default for new svn repositories!), there's a race
condition here. A logfile still active (or even non-existent) when the copy
begins (during step 1) might be deleted before being re-copied in step 2. The
result is that your backup may not be recoverable, due to incomplete logs.
This is a P1 problem... there's a chance that people are using 'svnadmin
hotcopy' out there and not getting working backups.
Here's an email with an example (from kfogel) of how to do backups on a
repository that is *not* doing automatic logfile removal. This should clarify
things:
http://subversion.tigris.org/servlets/ReadMsg?list=users&msgNo=9244