rsync behavior on copy-on-write filesystems

Kevin Korb kmk at
Wed May 22 15:35:17 MDT 2013

Hash: SHA1

You might find the lsh program in the support dir of the source tree
useful.  It is essentially the same as using ssh localhost but without
the overhead.

On 05/22/13 17:25, Allen Supynuk wrote:
> Sorry for the churn and thanks for the suggestions. When I redid
> my experiments over the network everything worked just as I dreamed
> it would. Changing the first 4K bytes only caused a 4K change in
> the copy. Changing meta-data (time stamp) only caused the time
> stamp to change in the copy.
> This is very nice and I expect it to save 10's of GB per archive
> going forward.
> Kevin was right. --whole-file was the default when source and 
> destination are specified as local paths.
> On 5/22/13, Allen Supynuk <allen.supynuk at> wrote:
>> Kevin,
>> I will try again over a remote connection to see if that makes a 
>> difference. Not expecting -z to day much of anything based on
>> the random data, just wanting to be consistent with the flags in
>> the finished solution.
>> Chris,
>> You only get --whole-file if you specify it (or -W).
>> Paul,
>> For my first couple of days of testing I dutifully did both 'df
>> -h .' and 'btrfs filesystem df .' until I saw that they give the
>> same answer after you wait for background cleanup. In this case
>> we are only adding files so no background cleanup applies.
>> On 5/22/13, Paul Slootman <paul+rsync at> wrote:
>>> On Tue 21 May 2013, Allen Supynuk wrote:
>>>> ## 1) Start with an empty filesystem
>>>> $ df -h .
>>> Note that you need to be using "btrfs filesystem df ." for
>>> reliable numbers; the normal df does not take into account 
>>> background cleanups etc.
>>> Paul -- Please use reply-all for most replies to avoid omitting
>>> the mailing list. To unsubscribe or change options: 
>>> Before posting,
>>> read:
>> -- Allen.Supynuk at

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