On 01/13/2013 12:30 AM, Gordon Messmer wrote:
If you want to make a backup that's consistent across a filesystem, you need to make a snapshot, mount it, and back up the snapshot content. If there are files open for writing, you need to make them consistent while the snapshot is made. While I rarely say nice things about Windows, this is an area where Linux falls far short. There is no common mechanism for making files and databases consistent and making a snapshot for backups. Admins must do this on their own. If you aren't actively taking steps to make your backups consistent, they aren't.
After publicly bitching about Linux's poor backup infrastructure for the hundredth time, I decided to write a system largely similar to VSS. I've written the first iteration in bash. It took one day to do most of the work, and then a few hours of testing and fixing to get things working reasonably well.
https://bitbucket.org/gordonmessmer/dragonsdawn-snapshot
At this point, there's enough working for other people to start looking at. Systems with ext3/4 filesystems on LVM are supported. btrfs will follow. PostgreSQL has a script to make its data consistent, but other common systems like MySQL, OpenLDAP, and 389 DS need similar support. Documentation needs to be written. A few architectural issues need to be ironed out.
If you're interested in improving the state of backups on GNU/Linux, please have a look and contact me if you want to help with code, testing, documentation, packaging, or maintaining packages in distributions so that this becomes a standard feature.