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[68.103.222.6]) by smtp.gmail.com with ESMTPSA id b12sm690199oti.17.2021.04.09.09.47.48 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Fri, 09 Apr 2021 09:47:48 -0700 (PDT) Subject: Re: [PATCH] Document qemu-img options data_file and data_file_raw To: John Snow , qemu-devel@nongnu.org References: <20210301172837.20146-1-ckuehl@redhat.com> <4e64ef24-ba3d-809c-6320-57965c353247@redhat.com> From: Connor Kuehl Message-ID: <6959b220-a722-6dd8-c444-b2434e7d72eb@redhat.com> Date: Fri, 9 Apr 2021 11:47:47 -0500 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:78.0) Gecko/20100101 Thunderbird/78.8.1 MIME-Version: 1.0 In-Reply-To: <4e64ef24-ba3d-809c-6320-57965c353247@redhat.com> Authentication-Results: relay.mimecast.com; auth=pass smtp.auth=CUSA124A263 smtp.mailfrom=ckuehl@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=ckuehl@redhat.com; helo=us-smtp-delivery-124.mimecast.com X-Spam_score_int: -27 X-Spam_score: -2.8 X-Spam_bar: -- X-Spam_report: (-2.8 / 5.0 requ) BAYES_00=-1.9, DKIMWL_WL_HIGH=-0.001, 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_H4=0.001, RCVD_IN_MSPIKE_WL=0.001, SPF_HELO_NONE=0.001, SPF_PASS=-0.001 autolearn=ham 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: hhan@redhat.com, stefanha@redhat.com, mreitz@redhat.com Errors-To: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Sender: "Qemu-devel" On 3/23/21 6:15 PM, John Snow wrote: > On 3/1/21 12:28 PM, Connor Kuehl wrote: >> [..] >> diff --git a/docs/tools/qemu-img.rst b/docs/tools/qemu-img.rst >> index b615aa8419..5cc585dc27 100644 >> --- a/docs/tools/qemu-img.rst >> +++ b/docs/tools/qemu-img.rst >> @@ -866,6 +866,18 @@ Supported image file formats: >>       issue ``lsattr filename`` to check if the NOCOW flag is set or not >>       (Capital 'C' is NOCOW flag). >> +  ``data_file`` >> +    Pathname that refers to a file that will store all guest data. If >> +    this option is used, the qcow2 file will only contain the image's >> +    metadata. >> + > > Might recommend "filename" simply for parity with *FILENAME* argument. > > (This is the first appearance of "Pathname" in this file without spaces, > though "Path name" is indeed used several times.) > >> +  ``data_file_raw`` >> +    If this option is set to ``on``, QEMU will always keep the external >> +    data file consistent as a standalone read-only raw image. The >> default >> +    value is ``off``. >> + >> +    This option can only be enabled if ``data_file`` is set. >> + > > How does this interact with caching options, if it does? What happens in > the negative case -- how does the file become inconsistent? Hi, First, just wanted to share the same note I'm sending to Max's review: > Hey, I just wanted to leave a note indicating that I'm not ignoring this review; I've incorporated it in my next version but I am waiting until after the freeze to send it. Second: I've been trying to figure out if and how this affects caching. I do not know yet. I will keep digging. My next version of the patch does touch on the negative case though, describing how it becomes inconsistent. Thank you! Connor