Backup file format that enables easy access of specific files?

Question

I need to upgrade a Server and there have to make a compressed backup of a lot of directories. The question is: Which format should I use? tar.gz, cpio? Both compression and decompression processes should be fast. In case I have some corruption on the Server later on, I want to be able to easily pick certain files out of my old backups.

Thanks, Philip

Answer 1

Good old standard tarballs allow for the extracting of a single file. For more detailed information, I would recommend you read the man page for tar. But, to get you started, here's a quick example :

# List content of a gzip compressed tar file
tar -tzf tarball.tgz
# Extract all contents of the gzip compressed tar file
tar -xzf tarball.tgz
# Extract filename from the gzip compressed tar file
tar -xzf tarball.tgz filename
# Extract filename*, same as above but from any directory within the tarball and using pattern expansion. 
tar -xzf --wildcards --no-anchored 'filename*'

Answer 2

You could use a read-only file system like squashfs. This will also compress the files. The advantage over tar, cpio is that getting a specific file is instant.

Another alternative is to use 7zip or zip, but not as a solid archive.