rsync --link-dest and --files-from lead by a "change list" from some file system audit tool (Was: Re: cut-off time for rsync ?)
Paul Slootman
paul+rsync at wurtel.net
Tue Jul 14 06:59:25 UTC 2015
On Mon 13 Jul 2015, Andrew Gideon wrote:
>
> On the other hand, I do confess that I am sometimes miffed at the waste
> involved in a small change to a very large file. Rsync is smart about
> moving minimal data, but it still stores an entire new copy of the file.
>
> What's needed is a file system that can do what hard links do, but at the
> file page level. I imagine that this would work using the same Copy On
> Write logic used in managing memory pages after a fork().
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.
Paul
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