After completing nfs_automount script a bit over a week ago, I soon realized rdiff-backup I had planned to use with the now-nearly-guaranteed-to-be-online NFS shares would not work. I then turned to my other favorite *NIX server backup solution, duplicity with duplicity-backup.sh wrapper script. It utilizes gzip-based archives, which works much better with NFS/CIFS shares. Besides the other odd problems with rdiff-backup and NFS, it resolves the more obvious issue with conflicting users/permissions between the client and the NFS share host as duplicity doesn’t maintain a direct mirrored copy of the files being backed up.
The only problem was that since duplicity creates incrementals, and I generally like to keep backups around for several months, the incrementals are really never needed beyond couple of weeks. Beyond that in my applications the day-by-day backups are overkill, and should be pruned. Duplicity provides an option to do so (“remove-all-inc-of-but-n-full”), but duplicity-backup.sh hadn’t implemented it, so I first contributed a patch to zertrin’s project. Then I proceeded to write a wrapper for the wrapper to add the extra pre-backup checks, and duplicity-nfs-backup was born.
So what is duplicity-nfs-backup? It is a wrapper script designed to ensure that an NFS/CIFS-mounted target directory is indeed accessible before commencing with backup. While duplicity-backup.sh can be used to back up to a variety of mediums (ftp, rsync, sftp, local file…), duplicity-nfs-backup is specifically intended to be used with NFS/CIFS shares as backup targets.
The script that was the impetus for writing duplicity-nfs-backup, nfs_automount, attempts to keep the NFS shares online at all times, but the client system can’t always help with such situations. What if the target system becomes unreachable due to a network problem? Or what if a disk, or a filesystem mount fails on the target while the share is still available? In any of these cases duplicity-backup/duplicity would back up into an empty mountpoint. duplicity-nfs-backup adds the necessary checks to ensure that this won’t happen, and it also issues log/syslog warnings when a backup fails due to a share that has gone M.I.A.
I mentioned earlier that duplicity-nfs-backup is “a wrapper for the wrapper.” Paraphrasing zertrin, it is important to note that duplicity-nfs-backup IS NEITHER duplicity, NOR is it duplicity-backup! It is only a wrapper script for duplicity-backup, also written in bash.
This means that you will need to install and configure duplicity and duplicity-backup.sh before you can utilize duplicity-nfs-backup. I also recommend that you would make use of nfs_automount as it significantly improves the chances that the NFS target share will be online when duplicity-nfs-backup attempts to access it.
This script is intended to be run from crontab. duplicity-nfs-backup takes no arguments, simply set the configuration parameters in duplicity-nfs-backup.conf and you’re done!
Like nfs_automount, duplicity-nfs-backup is also distributed under MIT license.
Clone or download duplicity-nfs-backup from my GitHub repository, and let me know if you come across any problems (or also if it works fantastically and saves the day! ). Pull requests are always welcome.