compare COW files

compare COW files

[calin]

If I make a cow copy of a file, is there a way find out whether either copy has changed?  Specifically, I'm looking for a way to figure out which files have changed since a snapshot was taken, short of traditional and time-consuming file comparisons.  It could have some interesting possibilities for monitoring and backup, to be able to quickly compare against a reference snapshot to find changes.

Re: compare COW files

[Joshua J. Berry]

On Monday 20 October 2008 20:25:52 calin wrote:
> If I make a cow copy of a file, is there a way find out whether either copy
> has changed?  Specifically, I'm looking for a way to figure out which files
> have changed since a snapshot was taken, short of traditional and
> time-consuming file comparisons.  It could have some interesting
> possibilities for monitoring and backup, to be able to quickly compare
> against a reference snapshot to find changes. --
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I'm also very interested in this, for incremental backups.  I use rdiff-backup 
currently, and being able to do this would likely give an impressive speed 
boost.

-- Josh


-- 
Joshua J. Berry

"I haven't lost my mind -- it's backed up on tape somewhere."
    -- /usr/games/fortune

Re: compare COW files

[Yan Zheng]

2008/10/21 calin <calin@splitreflection.com>:
> If I make a cow copy of a file, is there a way find out whether either copy has changed?  Specifically, I'm looking for a way to figure out which files have changed since a snapshot was taken, short of traditional and time-consuming file comparisons.  It could have some interesting possibilities for monitoring and backup, to be able to quickly compare against a reference snapshot to find changes.

Btrfs disk format already supports this. We will implement this in the
near future.

Regards
Yan Zheng