From: "Swâmi Petaramesh" <swami@petaramesh.org>
To: Marc Dietrich <marvin24@gmx.de>
Cc: linux-btrfs@vger.kernel.org
Subject: Re: nocow and compression
Date: Mon, 27 Oct 2014 14:10:42 +0100 [thread overview]
Message-ID: <1443833.UFNBsg354b@vajra> (raw)
In-Reply-To: <2583846.rYj5NyAvhi@fb07-iapwap2>
As far as I understood, "NOCOW" means that modified parts of files be rewritten
into place, whereas compression causes compressed blocks of variable sizes to
be created (depending upon their compression ratio). Changing a block in a file
will most probably change its compressed size, and then you see why it cannot
be rewritten into place...
Somebody correct me if I'm wrong ;-)
Le lundi 27 octobre 2014, 14:06:36 Marc Dietrich a écrit :
> >
> > « Compression does not work for NOCOW files » is clearly stated in
> >
> > https://btrfs.wiki.kernel.org/index.php/Compression#How_does_compression_i
> > nt eract_with_direct_IO_or_COW.3F
>
> ah, sorry, I somehow overlooked this.
>
> Thanks
>
> Marc
--
Swâmi Petaramesh <swami@petaramesh.org> http://petaramesh.org PGP 9076E32E
Tout être manifesté est là pour embaumer, pour exprimer la Présence.
-- Jean-Marc Mantel
prev parent reply other threads:[~2014-10-27 13:10 UTC|newest]
Thread overview: 4+ messages / expand[flat|nested] mbox.gz Atom feed top
2014-10-27 12:56 nocow and compression Marc Dietrich
2014-10-27 12:59 ` Swâmi Petaramesh
2014-10-27 13:06 ` Marc Dietrich
2014-10-27 13:10 ` Swâmi Petaramesh [this message]
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