Backup depends on what type whether Cold or Hot backup solution.
Could you afford a shutdown of the server and then do a rsync (linux utility)
to sync the alf_data folder. Hot backup expects you to do a hot back up
of the DB & rename the backup-lucene-indexes folder to lucene-indexes
Never do a rsync of live lucene-indexes folder, that might cause index failures.
rsync -vauz –delete –exclude 'lucene-indexes' –exclude 'lucene-indexes.old' /usr/local/alfresco/alf_dat
8 a root@server-ip:/usr/local/alfresco