From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-7.5 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,NICE_REPLY_A,SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED, USER_AGENT_SANE_1 autolearn=no autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 7B0CCC433E0 for ; Thu, 18 Mar 2021 19:52:14 +0000 (UTC) Received: from lists.gnu.org (lists.gnu.org [209.51.188.17]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPS id E601A64EE1 for ; Thu, 18 Mar 2021 19:52:13 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org E601A64EE1 Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=redhat.com Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Received: from localhost ([::1]:35064 helo=lists1p.gnu.org) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1lMygm-0000Qw-IJ for qemu-devel@archiver.kernel.org; Thu, 18 Mar 2021 15:52:12 -0400 Received: from eggs.gnu.org ([2001:470:142:3::10]:45574) by lists.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1lMyeq-0007yf-4h for qemu-devel@nongnu.org; Thu, 18 Mar 2021 15:50:20 -0400 Received: from us-smtp-delivery-124.mimecast.com ([216.205.24.124]:35932) by eggs.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1lMyeh-0001Z1-AV for qemu-devel@nongnu.org; Thu, 18 Mar 2021 15:50:11 -0400 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1616097001; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version:content-type:content-type: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=qX9bn47uYp+Jz8jpXv8OoUVv0ykOs2WnbjzEvvBmG9I=; b=P4k5OliJkVu+Nrf/XY/bfLaa3eI+F/T/mOvMI+n+ICKpRSeeAbWzeQYk5BqN285GRwi7h+ cD1QTSRUtW3hmgvydwl71AmSe8Syi7/sIQaYEdxD9+LzIQVxM7o8FxqC9CH7/2auTTS7iU WaQI1M2JDfaWuyA2mSe6WGsZAO7ktjA= Received: from mimecast-mx01.redhat.com (mimecast-mx01.redhat.com [209.132.183.4]) (Using TLS) by relay.mimecast.com with ESMTP id us-mta-269-g2A6RqIxNImCeL-F4VQJvg-1; Thu, 18 Mar 2021 15:49:56 -0400 X-MC-Unique: g2A6RqIxNImCeL-F4VQJvg-1 Received: from smtp.corp.redhat.com (int-mx01.intmail.prod.int.phx2.redhat.com [10.5.11.11]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mimecast-mx01.redhat.com (Postfix) with ESMTPS id 93553190A7A0; Thu, 18 Mar 2021 19:49:55 +0000 (UTC) Received: from [10.10.117.64] (ovpn-117-64.rdu2.redhat.com [10.10.117.64]) by smtp.corp.redhat.com (Postfix) with ESMTP id 2F5156C32F; Thu, 18 Mar 2021 19:49:55 +0000 (UTC) Subject: Re: How to create vhdx differencing disk using qemu-img To: qi zhou , "qemu-devel@nongnu.org" References: From: John Snow Message-ID: <3585d6b8-a94e-bd2e-5a38-6ddfc2fe089d@redhat.com> Date: Thu, 18 Mar 2021 15:49:54 -0400 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:78.0) Gecko/20100101 Thunderbird/78.8.0 MIME-Version: 1.0 In-Reply-To: X-Scanned-By: MIMEDefang 2.79 on 10.5.11.11 Authentication-Results: relay.mimecast.com; auth=pass smtp.auth=CUSA124A263 smtp.mailfrom=jsnow@redhat.com X-Mimecast-Spam-Score: 0 X-Mimecast-Originator: redhat.com Content-Type: text/plain; charset=utf-8; format=flowed Content-Language: en-US Content-Transfer-Encoding: 8bit Received-SPF: pass client-ip=216.205.24.124; envelope-from=jsnow@redhat.com; helo=us-smtp-delivery-124.mimecast.com X-Spam_score_int: -29 X-Spam_score: -3.0 X-Spam_bar: --- X-Spam_report: (-3.0 / 5.0 requ) BAYES_00=-1.9, DKIMWL_WL_HIGH=-0.249, DKIM_SIGNED=0.1, DKIM_VALID=-0.1, DKIM_VALID_AU=-0.1, DKIM_VALID_EF=-0.1, NICE_REPLY_A=-0.001, RCVD_IN_DNSWL_LOW=-0.7, RCVD_IN_MSPIKE_H3=0.001, RCVD_IN_MSPIKE_WL=0.001, SPF_HELO_NONE=0.001, SPF_PASS=-0.001 autolearn=unavailable autolearn_force=no X-Spam_action: no action X-BeenThere: qemu-devel@nongnu.org X-Mailman-Version: 2.1.23 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: Qemu-block Errors-To: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Sender: "Qemu-devel" On 3/17/21 10:37 PM, qi zhou wrote: > When I create vhdx differencing disk using qemu-img, It says >  qemu-img: xxx.vhd Backing file not supported for file format 'vhdx' > > The command I used is > qemu-img create -f vhdx -b test.vhdx test-snapshot.vhdx > > Here is my questions > 1. Is vhdx format [full] supported by qemu ? We support raw and qcow2 fully, read-write. Everything else is "read-only", though write support might work, we don't encourage its use in production environments. > 2. If not, is there any easy way to implement differencing disk of vhdx in qemu-img ? the -b flag is generally for qcow2 files; I am not very familiar with VHDX but it appears as though we don't support it here. I imagine it's https://www.altaro.com/hyper-v/hyper-v-differencing-disks-explained/ ? I don't think we support those... ah, yeah, in block/vhdx.c: typedef enum VHDXImageType { VHDX_TYPE_DYNAMIC = 0, VHDX_TYPE_FIXED, VHDX_TYPE_DIFFERENCING, /* Currently unsupported */ } VHDXImageType; > 3. Is there any other tools support vhdx on linux ? > Not that I'm aware of, but I can't say I've looked before.