On Wed, 27 Feb 2013, Ian Collins wrote:
Magic rsync options used:

    -a --inplace --no-whole-file --delete-excluded

This causes rsync to overwrite the file blocks in place rather than
writing to a new temporary file first.  As a result, zfs COW produces
primitive "deduplication" of at least the unchanged blocks (by writing
nothing) while writing new COW blocks for the changed blocks.

Do these options impact performance or reduce the incremental stream sizes?

I don't see any adverse impact on performance and incremental stream size is quite considerably reduced.

The main risk is that if the disk fills up you may end up with a corrupted file rather than just an rsync error. However, the snapshots help because an earlier version of the file is likely available.

I just use -a --delete and the snapshots don't take up much space (compared with the incremental stream sizes).

That is what I used to do before I learned better.

Bob Friesenhahn
bfrie...@simple.dallas.tx.us, http://www.simplesystems.org/users/bfriesen/
GraphicsMagick Maintainer,    http://www.GraphicsMagick.org/
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