From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from firstgate.proxmox.com (firstgate.proxmox.com [212.224.123.68]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature RSA-PSS (2048 bits)) (No client certificate requested) by lists.proxmox.com (Postfix) with ESMTPS id AD68FF60F for ; Fri, 16 Dec 2022 13:04:23 +0100 (CET) Received: from firstgate.proxmox.com (localhost [127.0.0.1]) by firstgate.proxmox.com (Proxmox) with ESMTP id 86043217DA for ; Fri, 16 Dec 2022 13:03:53 +0100 (CET) Received: from proxmox-new.maurer-it.com (proxmox-new.maurer-it.com [94.136.29.106]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature RSA-PSS (2048 bits)) (No client certificate requested) by firstgate.proxmox.com (Proxmox) with ESMTPS for ; Fri, 16 Dec 2022 13:03:49 +0100 (CET) Received: from proxmox-new.maurer-it.com (localhost.localdomain [127.0.0.1]) by proxmox-new.maurer-it.com (Proxmox) with ESMTP id D528B44868 for ; Fri, 16 Dec 2022 13:03:48 +0100 (CET) Message-ID: Date: Fri, 16 Dec 2022 13:03:38 +0100 MIME-Version: 1.0 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:102.0) Gecko/20100101 Thunderbird/102.5.0 Content-Language: en-US To: Thomas Lamprecht , Proxmox VE development discussion References: <20221202125452.54621-1-f.ebner@proxmox.com> <6d01e6cf-2a27-c838-98cf-38de45f12a2c@proxmox.com> From: Fiona Ebner In-Reply-To: <6d01e6cf-2a27-c838-98cf-38de45f12a2c@proxmox.com> Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit X-SPAM-LEVEL: Spam detection results: 0 AWL 0.029 Adjusted score from AWL reputation of From: address BAYES_00 -1.9 Bayes spam probability is 0 to 1% KAM_DMARC_STATUS 0.01 Test Rule for DKIM or SPF Failure with Strict Alignment NICE_REPLY_A -0.001 Looks like a legit reply (A) SPF_HELO_NONE 0.001 SPF: HELO does not publish an SPF Record SPF_PASS -0.001 SPF: sender matches SPF record Subject: Re: [pve-devel] [RFC qemu-server] migration: nbd export: switch away from deprecated QMP command X-BeenThere: pve-devel@lists.proxmox.com X-Mailman-Version: 2.1.29 Precedence: list List-Id: Proxmox VE development discussion List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Fri, 16 Dec 2022 12:04:23 -0000 Am 16.12.22 um 12:52 schrieb Thomas Lamprecht: > On 02/12/2022 13:54, Fiona Ebner wrote: >> The 'nbd-server-add' QMP command has been deprecated since QEMU 5.2 in >> favor of a more general 'block-export-add'. >> >> When using 'nbd-server-add', QEMU internally converts the parameters >> and calls blk_exp_add() which is also used by 'block-export-add'. It >> does one more thing, namely calling nbd_export_set_on_eject_blk() to >> auto-remove the export from the server when the backing drive goes >> away. But that behavior is not needed in our case, stopping the NBD >> server removes the exports anyways. >> >> It was checked with a debugger that the parameters to blk_exp_add() >> are still the same after this change. Well, the block node names are >> autogenerated and not consistent across invocations. >> >> The alternative to using 'query-block' would be specifying a >> predictable 'node-name' for our '-drive' commandline. It's not that >> difficult for this use case, but in general one needs to be careful >> (e.g. it can't be specified for an empty CD drive, but would need to >> be set when inserting a CD later). Querying the actual 'node-name' >> seemed a bit more future-proof. > > are there other examples than the CD-Drive, as that one wouldn't be > really relevant for us here or? Not relevant here, but I'd expect that *if* we introduce node-names, that we can rely on them in the future in other situations too. The CD drive example is the only one I found. > > IMO they key disadvantage of switching to computed node-names is the > upgrade path, as I'd expect that for running VMs we cannot change them > to computed ones and thus we would need to still query (or keep the > legacy command) for those... Since introduction of node-names and export happen on the fresh target instance there should not be an issue with the upgrade path.