[systemd-devel] [PATCH/resend] Use reflinking to copy kernel

Lennart Poettering lennart at poettering.net
Wed May 20 03:48:15 PDT 2015

On Tue, 19.05.15 02:33, Pádraig Brady (P at draigBrady.com) wrote:

> FYI...
> mv reflinks by default, but only in the unreleased V8.24 (Fedora 23).
> cp doesn't default to --reflink=auto as that would break the case where one uses copy
> for durability reasons to have a second copy of the data.  Also for performance reasons
> you may want the writes to happen at copy time rather than some latency sensitive process
> working on a CoW file and being delayed by the writes possibly to a different part of a mechanical disk.

I am pretty sure that both those usecases are of the more exotic kind,
and that reflinks should hence be the default, and people who want the
byte-by-byte kind of copy should request it explicitly with
--reflink=no or dd.

I think a good user interface make the common operations easy (and
hence default) and the exotic ones possible. For me that clearly means
that --reflink=auto should be the default, and --reflink=no the
option, and *not* the other way round...


Lennart Poettering, Red Hat

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