I fail to see why would you ask this question here on FreeBSD forum if you a planning to use Linux or NetBSD. ZFS has built backup system (ZFS replication). IIRC there was a tool in FreeBSD ports which will allow you to do UFS mirroring HAMMER stream style. I don't use UFS so I would not know.
First off the question you should ask yourself is what do you really want: journaling, backup, or arhiving? The only journaling file systems which are fully functional are ZFS and HAMMER1. ZFS appears to be more robust and it is no brainier for people who have any significant amount of data (more than 20TB). ZFS runs on Linux and some people swear by it but I am not the one of them. Journaling on ZFS is done using periodic snapshots. HAMMER has a built in fine grained journaling (hammer history). HAMMER does support snapshots as well but they have a slightly different role than ZFS snapshots (they are not needed for mirror streaming unlike ZFS snapshots which are needed for ZFS replication). Backup with ZFS and HAMMER is trivial. ZFS uses replication for backup while HAMMER has mirror-stream command. Both are network aware. Both are well tested and in the case of ZFS used by some of the large data centres in U.S. As I mentioned earlier IIRC there is a port which can do something similar with UFS. Obviously RAID 1 gives you the illusion of backup. I like better hardware RAID. Archiving I am not sure. We don't archive much data in my Lab. I really like
sysutils/duplicity if you ask me as archiving tool. Many people appear to use duplicity with Amazon glacier. I should mentioned that our own Colin Percival has cloud archiving tool
http://www.tarsnap.com/ which uses Amazon to store encrypted data.
The only thing I think ZFS seems ill suited (somebody will correct me with this one if I am wrong) is being backed up on the tape. FreeNAS people have always in the past removed tape drivers from their version of the kernel. I have seen very few thread where people describe backing up ZFS to the tape.
In real life besides OpenBSD and FreeBSD I also run RHEL on over two dozen large computing nodes (60 cores + 1TB of RAM) and about 2 dozen or more of desktops in my Lab. I use
sysutils/rsnapshot to backup user directories (XFS file system) onto the remote server which happens to run FreeBSD. The tool works perfectly. I use it also at home to backup my OpenBSD desktop onto an OpenBSD file server. We don't backup RHEL computing nodes. In the past I had one or two file servers running RHEL and we were relaying on the hardware RAID 6 as I backup strategy. I would strongly discourage such practice. We used high end LSI cards but I also like very much Areca cards. I honestly can't think of anything in Linux world which comes close to ZFS replication. For the record LSI RAID6+XFS is robust industry solution and I would not hesitate twice to put 200-300 TB on it. Maybe you should look
misc/amanda or something similar.I think I was running
net/rsync cronjob to backup RHEL file servers but that is not very robust.
NetBSD is on a dead bed if you ask me. It has WABPL which is really cool but other than that and npf there has been nothing original coming out of that camp for a long time. They have no fancy file system. Their softraid stack is 10 year old research code (I should know as it came out of CMU where I work). I am not sure if you can use any serious RAID cards on NetBSD except of course Areca which is open hardware. Again I would not know how you could monitor your hardware RAID. Again RAID is not backup so that would not solve anything anyway.