From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([208.118.235.92]:42488) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1TbAHi-0006Lv-Fi for qemu-devel@nongnu.org; Wed, 21 Nov 2012 08:24:19 -0500 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1TbAHa-00017K-Uw for qemu-devel@nongnu.org; Wed, 21 Nov 2012 08:24:10 -0500 Received: from mx1.redhat.com ([209.132.183.28]:35587) by eggs.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1TbAHa-000173-NX for qemu-devel@nongnu.org; Wed, 21 Nov 2012 08:24:02 -0500 Received: from int-mx01.intmail.prod.int.phx2.redhat.com (int-mx01.intmail.prod.int.phx2.redhat.com [10.5.11.11]) by mx1.redhat.com (8.14.4/8.14.4) with ESMTP id qALDO2JH022730 (version=TLSv1/SSLv3 cipher=DHE-RSA-AES256-SHA bits=256 verify=OK) for ; Wed, 21 Nov 2012 08:24:02 -0500 From: Kevin Wolf Date: Wed, 21 Nov 2012 14:23:57 +0100 Message-Id: <1353504237-5608-3-git-send-email-kwolf@redhat.com> In-Reply-To: <1353504237-5608-1-git-send-email-kwolf@redhat.com> References: <1353504237-5608-1-git-send-email-kwolf@redhat.com> Subject: [Qemu-devel] [PATCH 2/2] Documentation: Update image format information List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: stefanha@redhat.com Cc: kwolf@redhat.com, qemu-devel@nongnu.org Document new options, mark QED as deprecated. Signed-off-by: Kevin Wolf --- qemu-img.texi | 37 ++++++++++++++++++++++++++++++------- 1 files changed, 30 insertions(+), 7 deletions(-) diff --git a/qemu-img.texi b/qemu-img.texi index 60b83fc..2fdb3ef 100644 --- a/qemu-img.texi +++ b/qemu-img.texi @@ -247,6 +247,13 @@ support of multiple VM snapshots. Supported options: @table @code +@item compat +Determines the qcow2 version to use. @code{compat=0.10} uses the traditional +image format that can be read by any QEMU since 0.10 (this is the default). +@code{compat=1.1} enables image format extensions that only QEMU 1.1 and +newer understand. Amongst others, this includes zero clusters, which allow +efficient copy-on-read for sparse images. + @item backing_file File name of a base image (see @option{create} subcommand) @item backing_fmt @@ -267,14 +274,23 @@ Preallocation mode (allowed values: off, metadata). An image with preallocated metadata is initially larger but can improve performance when the image needs to grow. +@item lazy_refcounts +If this option is set to @code{on}, reference count updates are postponed with +the goal of avoiding metadata I/O and improving performance. This is +particularly interesting with @option{cache=writethrough} which doesn't batch +metadata updates. The tradeoff is that after a host crash, the reference count +tables must be rebuilt, i.e. on the next open an (automatic) @code{qemu-img +check -r all} is required, which may take some time. + +This option can only be enabled if @code{compat=1.1} is specified. + @end table @item qed -Image format with support for backing files and compact image files (when your -filesystem or transport medium does not support holes). Good performance due -to less metadata than the more featureful qcow2 format, especially with -cache=writethrough or cache=directsync. Consider using qcow2 which will soon -have a similar optimization and is most actively developed. +Old QEMU image format. Left for compatibility. + +For new images, use qcow2 instead. You might want to consider using the +@code{lazy_refcounts=on} option to get a more QED-like behaviour. Supported options: @table @code @@ -315,10 +331,17 @@ VMware 3 and 4 compatible image format. Supported options: @table @code -@item backing_fmt -Image format of the base image +@item backing_file +File name of a base image (see @option{create} subcommand). @item compat6 Create a VMDK version 6 image (instead of version 4) +@item subformat +Specifies which VMDK subformat to use. Valid options are +@code{monolithicSparse} (default), +@code{monolithicFlat}, +@code{twoGbMaxExtentSparse}, +@code{twoGbMaxExtentFlat} and +@code{streamOptimized}. @end table @item vpc -- 1.7.6.5