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[87.0.86.235]) by smtp.googlemail.com with ESMTPSA id a640c23a62f3a-ab2c9060db6sm72320366b.8.2025.01.09.05.19.40 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Thu, 09 Jan 2025 05:19:41 -0800 (PST) Message-ID: <483058af-44d9-441c-98df-fd7150184ebe@m2r.biz> Date: Thu, 9 Jan 2025 14:19:38 +0100 MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [pve-devel] [PATCH v3 qemu-server 11/11] qcow2: add external snapshot support To: Proxmox VE development discussion , =?UTF-8?Q?Fabian_Gr=C3=BCnbichler?= References: <20241216091229.3142660-1-alexandre.derumier@groupe-cyllene.com> <570013533.830.1736423850641@webmail.proxmox.com> Content-Language: it From: Fabio Fantoni In-Reply-To: <570013533.830.1736423850641@webmail.proxmox.com> Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 8bit X-Antivirus: Avast (VPS 250109-2, 9/1/2025), Outbound message X-Antivirus-Status: Clean X-SPAM-LEVEL: Spam detection results: 0 BAYES_00 -1.9 Bayes spam probability is 0 to 1% DKIM_SIGNED 0.1 Message has a DKIM or DK signature, not necessarily valid DKIM_VALID -0.1 Message has at least one valid DKIM or DK signature DMARC_PASS -0.1 DMARC pass policy JMQ_SPF_NEUTRAL 0.5 SPF set to ?all KAM_INFOUSMEBIZ 0.75 Prevalent use of .info|.us|.me|.me.uk|.biz|xyz|id|rocks|life domains in spam/malware RCVD_IN_DNSWL_NONE -0.0001 Sender listed at https://www.dnswl.org/, no trust SPF_HELO_NONE 0.001 SPF: HELO does not publish an SPF Record SPF_PASS -0.001 SPF: sender matches SPF record Il 09/01/2025 12:57, Fabian Grünbichler ha scritto: >> Alexandre Derumier via pve-devel hat am 16.12.2024 10:12 CET geschrieben: > it would be great if there'd be a summary of the design choices and a high level summary of what happens to the files and block-node-graph here. it's a bit hard to judge from the code below whether it would be possible to eliminate the dynamically named block nodes, for example ;) > > a few more comments documenting the behaviour and ideally also some tests (mocking the QMP interactions?) would be nice @Alexandre Derumier: Thanks for add external snapshot support, I have not looked at the implementation in detail because I do not have enough time but I think external snapshot support would be useful. I used it outside of proxmox years ago, on Debian servers with VMs managed with libvirt, I managed external snapshots completely manually from cli with multiple commands because they were not implemented in virtmanager and they were useful to save a lot of time (instead of backup/restore) in some high-risk operations on VMs with large disks, raw pre-allocated on hdd disks. I used them very little and kept them only the minimum time necessary for delicate maintenance operations, if there were unforeseen events it returned to the situation before the snapshot, I deleted the external snapshot and created another one to try again, if instead everything was ok in the end I did the commit, and went back to using only the pre-allocated raw image. With high disk usage as in the operations I was doing the performance decrease with external qcow2 snapshots compared to just pre-allocated raw disks was huge if I remember correctly (which is why I used them for the minimum amount of time possible). If it hasn't already been planned I think it could be useful to warn users (atleast in documentation) to avoid them underestimating their possible impact on performance (especially if they basically have pre-allocated raw on hdd disks for greater performance and minimal defragmentation) and avoid use or keep them for a long time without real need. Another important thing to notify users is the increase in space usage (again mainly for those who are used to pre-allocated disks where they usually don't risk increases in space). In this implementation I don't see the possibility of using them on raw disks (on files) from a fast look, or am I wrong? If so, why? I think the main use would be in cases like that where you don't have snapshot support by default -- Questa email è stata esaminata alla ricerca di virus dal software antivirus Avast. www.avast.com --===============0134017791333959120== Content-Type: text/plain; charset="us-ascii" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit Content-Disposition: inline _______________________________________________ pve-devel mailing list pve-devel@lists.proxmox.com https://lists.proxmox.com/cgi-bin/mailman/listinfo/pve-devel --===============0134017791333959120==--