From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([2001:4830:134:3::10]:42149) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1dUYcp-0007Vd-L9 for qemu-devel@nongnu.org; Mon, 10 Jul 2017 09:21:20 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1dUYco-0005fU-Le for qemu-devel@nongnu.org; Mon, 10 Jul 2017 09:21:19 -0400 Date: Mon, 10 Jul 2017 15:21:06 +0200 From: Kevin Wolf Message-ID: <20170710132106.GF5772@noname.redhat.com> References: <1498733831-15254-1-git-send-email-pl@kamp.de> <1498733831-15254-5-git-send-email-pl@kamp.de> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <1498733831-15254-5-git-send-email-pl@kamp.de> Subject: Re: [Qemu-devel] [PATCH V2 4/8] qemu-img: add documentation for compress settings List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: Peter Lieven Cc: qemu-block@nongnu.org, qemu-devel@nongnu.org, lersek@redhat.com, den@openvz.org, mreitz@redhat.com, eblake@redhat.com, berrange@redhat.com Am 29.06.2017 um 12:57 hat Peter Lieven geschrieben: > Signed-off-by: Peter Lieven > --- > qemu-img.texi | 21 +++++++++++++++++++++ > 1 file changed, 21 insertions(+) > > diff --git a/qemu-img.texi b/qemu-img.texi > index 5b925ec..430f0b9 100644 > --- a/qemu-img.texi > +++ b/qemu-img.texi > @@ -621,6 +621,27 @@ file which is COW and has data blocks already, it couldn't be changed to NOCOW > by setting @code{nocow=on}. One can issue @code{lsattr filename} to check if > the NOCOW flag is set or not (Capital 'C' is NOCOW flag). > > +@item compress.format > +Defines which compression algorithm is should be used for compressed clusters. > +The following options are available if support for the respective libraries > +has been enabled at compile time: > + > + zlib Uses standard zlib compression > + > +The compression algorithm can only be defined at image create time and cannot > +be changed later. > + > +Note: defining a compression format will result in the compression format > + extension being written to the Qcow2 image. Older versions of QEMU will > + not be able to open images with this extension. Why not more specifically "QEMU versions before 2.10"? > +@item compress.level > +Defines which compression level is used for the selected compression format. > +The default of @code{compress.level=0} will use the default compression level > +for the format. Alternate values range from 1 for fastest compression to > +x for the best compression (x max vary between compression formats). This is > +always a trade in of compression speed against compressed size. Start with something like "valid for compress.format=zlib" and then give the exact range of valid values for zlib. Kevin