I just realized that busy files are pretty much impossible to deal with no matter what. If DB is in the middle of the transaction, then a "snapshot" based backup will work (we simply loose that transaction data as it is equivalent to crash). Other busy files might be corrupted if those files don't use transaction model.
I am not convinced that rsync can handle all device type files, all types of links and other attributes I don't even know about. I am not convinced that anyone actually restored file system using rsync. Does it really work? I personally use rsync to synchronize data for application deployment and it works great. But I usually have no special files to worry about. On Fri, May 5, 2017 at 1:35 PM, Sergei G <sergeig.pub...@gmail.com> wrote: > it would be naive at best to think that busy files can be handled at > application level. No, rsync cannot handle the problem of entire file > system dump. Neither it is safe to handle all special file cases. I am > thinking about sparse files (if Linux has those). > > On Thu, May 4, 2017 at 11:52 PM, Dejan Jocic <jode...@gmail.com> wrote: > >> On 04-05-17, Sergei G wrote: >> > That's good to know. >> > >> > >> > Thank you >> > >> > >> > On 5/4/17 6:46 PM, Anders Andersson wrote: >> > > On Fri, May 5, 2017 at 1:17 AM, Sergei G <sergeig.pub...@gmail.com> >> wrote: >> > > > I would like a backup tool that does not bring a million >> dependencies with >> > > > MBs of files. Something that works on server without X Windows and >> can send >> > > > backup to an externally attached USB drive. Nothing fancy. No >> network >> > > > infrastructure. Incremental backups would be greatly appreciated. >> Ability >> > > > to pipe to a compression program is a plus, just like I did with >> dump. >> > > > [...] >> > > > Any advice would be greatly appreciated. >> > > You won't like my solution, and it doesn't work with your current >> > > setup because it requires a specific file system: btrfs[1]. I'm >> > > posting it here for two reasons: >> > > 1) You might consider using btrfs on new installs >> > > 2) Someone else may search and find the thread >> > > >> > > After switching to btrfs I can now take instant snapshots of selected >> > > filesystems, transfer these to remote servers for backup, and most >> > > important: btrfs can track the *exact difference* between two >> > > snapshots taken over time, and only transfer the changes. All of this >> > > is very quick, because the filesystem already knows exactly what >> > > changed: Permission bits, file sizes, deleted files, changed data, >> > > whatever, all is already kept in a log. It also means that nothing >> > > will be missed, for example ACL bits etc. >> > > >> > > The delta is just a simple stream of data that can be compressed if >> > > necessary. Typically it is transmitted to a backup server where it is >> > > "replayed" so that you have a full clone of the original system.[2] >> > > >> > > In debian I use the little tool, btrbk[3], to automate all of this. >> > > You can simply do it manually if you want. >> > > >> > > [1] https://btrfs.wiki.kernel.org/index.php/Main_Page >> > > [2] https://btrfs.wiki.kernel.org/index.php/Incremental_Backup >> > > [3] https://github.com/digint/btrbk >> > > >> > >> >> Perhaps rsync can do the job for you? >> >> >
