Problem with running backups

Our backups using the rake backup utility are running more than 24 hours. Can anyone explain why it take so long? Does the backup wait until there is no activity on an open file before it backs it up. Can a backup tool like Avamar that does a file system backup be used? How will it handle open files? Can rsynch be used? Can anyone suggest a better way to do the backups? Is there a way to federate the repositories that would help?