rsync - Feb 2012 - [Bug 8740] New: compress ("-z") should be ignored if both src and dst are local

https://bugzilla.samba.org/show_bug.cgi?id=8740

           Summary: compress ("-z") should be ignored if both src and
dst
                    are local
           Product: rsync
           Version: 3.1.0
          Platform: All
        OS/Version: All
            Status: NEW
          Severity: trivial
          Priority: P5
         Component: core
        AssignedTo: wayned at samba.org
        ReportedBy: mailinglists35 at gmail.com
         QAContact: rsync-qa at samba.org


I once read the manual and remembered my favorite combination of parameters,
which includes "-z"
A couple of days ago I manually started a rsync copy between a local source and
a local destination. Today after screen -x I discovered the rsync is still
running and taking 95% of the cpu. After a bit of wtf'ing around I finally
carefully looked at rsync parameters and noticed my "-z" parameter.

Stopping rsync and restarting without compression brought disk traffic back to
expected.

Truth is I never expected compression to be enabled when copying from local to
local: why would rsync activate compression if both source and destinations are
local, anyway?

A default behaviour to match this expectation would probably save others.

Thanks.

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https://bugzilla.samba.org/show_bug.cgi?id=8740

--- Comment #1 from Brian K. White <brian at aljex.com> 2012-02-02
18:23:46 UTC ---
No please do not. If I specify an option, I want that option. If I do not want
that option, I will not specify that option.

At most, add a new option that modifies the behavior of -z a la
--skip-compress.

It's true I can't honestly think of a specific reason off hand, other
than
benchmarking and intentionally exercising (not invalid uses already), where
I'd
want to -z locally, I don't think it would even help where "local"
includes
nfs/samba mounts,

but,

It's also true that since I first used rsync in... 1998 or 1999, I never
considered this a problem. One mans automatic convenience is another mans
"dammned automagical behavior is doing what makes sense in the common case
_at
the expense of_ what I need in this case".

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https://bugzilla.samba.org/show_bug.cgi?id=8740

roland <devzero at web.de> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
                 CC|                            |devzero at web.de

--- Comment #2 from roland <devzero at web.de> 2013-12-25 20:47:19 UTC
---
>why would rsync activate compression if both source and 
>destinations are local, anyway
Because you told rsync to do so. 

hereby, i also give my vote to NOT include such feature in rsync

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