rdup-backups(1) - Linux man page

Name

rdup-backups - introduction into making backups with rdup

Work in Progress

This is entire document is a work in progress.

Introduction

rdup is a simple program that prints out a list of files and directories that are changed changed on a filesystem. It is much more sophisticated than for instance find, because rdup will find files that are removed are directories that are renamed. By glueing rdup together with a few very simple shell and perl scripts you can create a simple to understand, but powerfull backup solution. rdup includes a few scripts to make backups and restores easy to perform. rdup supports remote, encrypted and compressed backups.

It is always best to backup to another medium, be it a different local harddisk or a NFS mounted filesystem or use the remote backup capabilities to securely copy the backup to another system all together.

There is one wrapper script for rdup to make backups. This is rdup-simple. It uses a hardlinked backup scheme where each day has its own directory. This wrapper calls; rdup, rdup-snap and rdup-snap-link. It further more supports encryption, compressions and remote backups. This works by inserting the apropiate rdup helper utility in the pipeline.

rdup can be used to create a backup and to restore from a backup. In either case it is a matter a generating a list of files and copying them somewhere else.

Backup and Restore

Because making a backup means copying a list of files somewhere else and restoring is essentially the same operation, albeit the other way around, rdup can be used for both.

Backing Up with Rdup-simple

When using rdup-simple the backup process consists out of two phases. During phase one a copy is made of any previous backups backups. This a hardlinked copy, meaning that it will take up very little space. It uses GNU 'cp -l' to make this copy. See the manual page of rdup-snap-link for more information. rdup-simple uses ~/.rdup as the directory to write its internal filelist and timestamp file.

In phase two, rdup-simple will only update the files that are changed since the last backup. For these files the hardlink is removed or overwritten with a new version of the file. The net result is that each backup represents a complete view of your filesystem.

With rdup-simple you have a full view on what your filesystem looked like at any specific date. I personly keep about 3 months of backups and I can go back to any specific date in that time frame.

Examples

Local Backups

Backing up my homedir to the backup directory:

rdup-simple ~ /vol/backup/$HOSTNAME

This will create a backup in /vol/backup/$HOSTNAME/200705/15. So each day will have its own directory. Multiple sources are allowed, so:

rdup-simple ~ /etc/ /var/lib /vol/backup/$HOSTNAME

Will backup your homedirectory, /etc and /var/lib to the backup location. Also if you need to compress your backup, simple add a '-z' switch:

rdup-simple -z ~ /etc/ /var/lib /vol/backup/$HOSTNAME

Remote Backups

For a remote backup to work, both the sending machine and the receiving machine must have rdup installed. The currently implemented protocol is ssh.

Dumping my homedir to the remote server:

rdup-simple ~ ssh://miekg@remote/vol/backup/$HOSTNAME

The syntax is almost identical only the destination starts with the magic string 'ssh://'. Compression and encryption are just as easily enabled as with a local backup, just add '-z' and/or a '-k keyfile' argument:

rdup-simple -z -k 'secret-file' ~ ssh://miekg@remote/vol/backup/$HOSTNAME

Restore

In principle a restore is as easy as using the standard system tools to copy a directory to another location. However when the -a flag is used extended attributes are set, these are normally not read by the unix utilities. In this case you should restore by using rdup-snap -R to copy the files to another location. But there is also a script that can be used: rdup-restore.

Local Restore

Restoring my homedir to a temporaty directory:

rdup-restore /vol/backup/$HOSTNAME/200705/14/home/miekg

And ofcourse the compression and encryption also works here, so to restore a compressed backup you need only to add the 'z' flag:

rdup-restore -z /vol/backup/$HOSTNAME/200705/14/home/miekg /tmp/restore-miek

Remote Restore

When doing a remote restore the files are pulled from the remote server and then copied to your local server.

rdup-restore ssh://miek@remote/vol/backup/$HOSTNAME /tmp/restore

Compression and encryption will work as expected.

Referenced By

rdup-simple(1), rdup-snap-link(1), rdup-snap-link(8)