rsync --link-dest and --files-from lead by a "change list" from some file system audit tool (Was: Re: cut-off time for rsync ?)

[Andrew Gideon]

On Tue, 14 Jul 2015 08:59:25 +0200, Paul Slootman wrote:

> btrfs has support for this: you make a backup, then create a btrfs
> snapshot of the filesystem (or directory), then the next time you make a
> new backup with rsync, use --inplace so that just changed parts of the
> file are written to the same blocks and btrfs will take care of the
> copy-on-write part.

That's interesting.  I'd considered doing something similar with LVM 
snapshots.  I chose not to do so because of a particular failure mode: if 
the space allocated to a snapshot filled (as a result of changes to the 
"live" data), the snapshot would fail.  For my purposes, I'd want the new 
write to fail instead.  Destroying snapshots holding backup data didn't 
seem a reasonable choice.

How does btrfs deal with such issues?

	- Andrew