Re: btrfs send reproducibly fails for a specific subvolume after sending 15 GiB, scrub reports no errors

[Duncan <1i5t5.duncan@cox.net>]

Hugo Mills posted on Tue, 24 Nov 2015 21:27:46 +0000 as excerpted:

[In the context of btrfs send...]

>    -p only sends the file metadata for the changes from the reference
> snapshot to the sent snapshot. -c sends all the file metadata, but will
> preserve the reflinks between the sent snapshot and the (one or more)
> reference snapshots. You can only use one -p (because there's only one
> difference you can compute at any one time), but you can use as many -c
> as you like (because you can share extents with any number of subvols).
> 
>    In both cases, the reference snapshot(s) must exist on the
> receiving side.
> 
>    In implementation terms, on the receiver, -p takes a (writable)
> snapshot of the reference subvol, and modifies it according to the
> stream data. -c makes a new empty subvol, and populates it from scratch,
> using the reflink ioctl to use data which is known to exist in the
> reference subvols.

Thanks, Hugo.  I had a vague idea that the above was the difference in 
general, but as CAM says, the manpage (and wiki) isn't particularly 
detailed on the differences, so I didn't know whether my vague idea was 
correct or not.  Your explanation makes perfect sense and clears things 
up dramatically. =:^)

-- 
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"Every nonfree program has a lord, a master --
and if you use the program, he is your master."  Richard Stallman