From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from firstgate.proxmox.com (firstgate.proxmox.com [212.224.123.68]) by lore.proxmox.com (Postfix) with ESMTPS id 32F421FF166 for ; Wed, 11 Sep 2024 11:12:06 +0200 (CEST) Received: from firstgate.proxmox.com (localhost [127.0.0.1]) by firstgate.proxmox.com (Proxmox) with ESMTP id 8209B9A72; Wed, 11 Sep 2024 11:12:06 +0200 (CEST) Message-ID: <6a44716a-88bc-4523-b210-d67031917d8f@proxmox.com> Date: Wed, 11 Sep 2024 11:11:29 +0200 MIME-Version: 1.0 User-Agent: Mozilla Thunderbird To: Proxmox VE development discussion References: Content-Language: en-US From: Fiona Ebner In-Reply-To: X-SPAM-LEVEL: Spam detection results: 0 AWL -0.057 Adjusted score from AWL reputation of From: address BAYES_00 -1.9 Bayes spam probability is 0 to 1% DMARC_MISSING 0.1 Missing DMARC policy KAM_DMARC_STATUS 0.01 Test Rule for DKIM or SPF Failure with Strict Alignment RCVD_IN_VALIDITY_CERTIFIED_BLOCKED 0.001 ADMINISTRATOR NOTICE: The query to Validity was blocked. See https://knowledge.validity.com/hc/en-us/articles/20961730681243 for more information. RCVD_IN_VALIDITY_RPBL_BLOCKED 0.001 ADMINISTRATOR NOTICE: The query to Validity was blocked. See https://knowledge.validity.com/hc/en-us/articles/20961730681243 for more information. RCVD_IN_VALIDITY_SAFE_BLOCKED 0.001 ADMINISTRATOR NOTICE: The query to Validity was blocked. See https://knowledge.validity.com/hc/en-us/articles/20961730681243 for more information. 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] qcow2 internal snapshot: 4k write speed reduce to 100~200 iops on ssd ? 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: , Reply-To: Proxmox VE development discussion Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Errors-To: pve-devel-bounces@lists.proxmox.com Sender: "pve-devel" Hi, Am 30.08.24 um 18:01 schrieb DERUMIER, Alexandre via pve-devel: > Hi, > > I was doing tests with gfs2 && ocfs2, > > and I have notice 4k randwrite iops going from 20000 iops to > 100~200iops when a snapshot is present. > > I thinked it was related to gfs2 && ocfs2 allocation, > but I can reproduce too with a simple qcow2 file on > a local ssd drive. > Is the performance drop also this big with the local storage? > is it expected ? > > (I don't have use qcow2 snapshot since 10year, so I really don't > remember performance). > A performance drop is of course expected, because AFAIU it needs to do COW for the sectors that the snapshot references, but the drop does sound rather dramatic in your case. The performance should be better again once the COW is done, e.g. when running another test afterwards. I quickly tested in a nested VM with qcow2 disk on a directory storage and --numjobs=4: ran test, got ~33k IOPS made a snapshot ran test, got ~20k IOPS (it starts out very slow and then recovers) ran test, got ~33k IOPS again Best Regards, Fiona > > Using external snapshot file, I'm around 10000iops. > > test inside the vm: > > fio --filename=/dev/sdX --ioengine=libaio --direct 1 --bs=4k -- > rw=randwrite --numjobs=64 > > _______________________________________________ pve-devel mailing list pve-devel@lists.proxmox.com https://lists.proxmox.com/cgi-bin/mailman/listinfo/pve-devel