backing up your home folder

2 minute read (428 words)

Here I outline the solution I chose for backing up my life, er… I mean home folder. (I’m sure there’s life outside /home/tim somewhere…)

My requirements were:

  • backup to dvd+rw
  • >20GB of data to back up
  • no obscure formats (in case I don’t have the backup tool when I need to restore)

I looked at several solutions for backups but ended up writing scripts to meet my needs.

The main script creates a tar file of my home directory, excluding certain items, which is then split into files suitable for writing to dvd+rw discs, with tar based verification, md5sums and file list text files created at the same time.

The reason for splitting to 3 files per disc is that the iso 9660 spec has a 2GB file size limit, and it’s important that the discs are as simple as possible (ie no UDF) to aid recovery in awkward situations. This is also why I avoided compression.

#!/bin/bash -v  
#DVD+R SL capacity 4,700,372,992 bytes DVD, (see [wikipedia on DVD](  
#ISO max file size 2GB. 4.38GB/3 = 1,566,790,997bytes = 1,494MB  
#1,490MB to leave some space for listings and checksums  
tar -cvv --directory /home tim --exclude-from backup_home_exclude.txt | split -b 1490m - /var/backups/tim/home/home.tar.split.  
cd /var/backups/tim/home  
md5sum home.tar.split.* > home.md5  
cat home.tar.split.* | tar -t > home_file_list.txt  
cat home.tar.split.* | tar -d --directory /home tim > home_diff.txt  
ls -l home.* > home_backup_files.txt



This leaves me with a big pile of split files (named .aa, .ab etc) and a few text files. I proceeded to write 3 split files per disc, and put the 4 text files on every disc for convenience. I used gnome’s built in DVD writing to create the discs.

I also wanted to verify the md5 checksums as the discs were created, so I wrote another little script to make life easier. This ensures the newley written disc has been remounted properly, and runs the md5 check. So long as the 3 relevant checksums came out correctly on each disc I can be reasonably confident of recovering the data should I need it.
“eject -t” closes the cdrom, which is handy.  
#!/bin/bash -v  
cd /media  
eject -t  
mount /media/cdrom  
cd cdrom  
md5sum -c home.md5  
cd /media  

In addition to the above mechanism (which is a pain at best, mostly due to media limitations) I keep my machines in sync with unison which I strongly recommend for both technical and non-technical users. I gather it also runs on microsoft (who?), so you might find it useful if you are mid transition.

Tweet This || Post to LinkedIn || Page Source

Subscribe for updates on software development, contracting, side projects, blog posts and who knows what else. Read the archives for an idea of content.

Mailing list powered by the excellent