From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from firstgate.proxmox.com (firstgate.proxmox.com [IPv6:2a01:7e0:0:424::9]) by lore.proxmox.com (Postfix) with ESMTPS id 1C4E01FF15C for ; Fri, 25 Jul 2025 14:21:59 +0200 (CEST) Received: from firstgate.proxmox.com (localhost [127.0.0.1]) by firstgate.proxmox.com (Proxmox) with ESMTP id F123B17ABC; Fri, 25 Jul 2025 14:23:19 +0200 (CEST) Message-ID: <3027d138-99d3-419c-a124-7edc8a4f5623@proxmox.com> Date: Fri, 25 Jul 2025 14:22:44 +0200 MIME-Version: 1.0 User-Agent: Mozilla Thunderbird To: pve-devel@lists.proxmox.com References: <20250725113922.99886-1-f.weber@proxmox.com> <73cae5cf-3035-4cb8-9583-c71d7a8fd337@proxmox.com> Content-Language: en-US From: Mira Limbeck In-Reply-To: <73cae5cf-3035-4cb8-9583-c71d7a8fd337@proxmox.com> X-Bm-Milter-Handled: 55990f41-d878-4baa-be0a-ee34c49e34d2 X-Bm-Transport-Timestamp: 1753446160987 X-SPAM-LEVEL: Spam detection results: 0 AWL 0.290 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] [PATCH docs v2] pvecm, network: add section on corosync over bonds 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" On 7/25/25 13:50, Friedrich Weber wrote: > On 25/07/2025 13:39, Friedrich Weber wrote: >> [...] >> +Corosync Over Bonds >> +~~~~~~~~~~~~~~~~~~~ >> + >> +Using a xref:sysadmin_network_bond[bond] as the only Corosync link can be >> +problematic in certain failure scenarios. If one of the bonded interfaces fails >> +and stops transmitting packets, but its link state stays up, some bond modes >> +may cause a state of asymmetric connectivity where cluster nodes can only >> +communicate with different subsets of other nodes. In case of asymmetric >> +connectivity, Corosync may not be able to form a stable quorum in the cluster. >> +If this state persists and HA is enabled, nodes may fence themselves, even if >> +their respective bond is still fully functioning. In the worst case, the whole >> +cluster may fence itself. >> + >> +For this reason, our recommendations are as follows. >> + >> +* We recommend a dedicated physical NIC for the primary Corosync link. Bonds >> + can be used as additional links for increased redundancy. > > These recommendations are still not 100% clear: Are we fine with a setup > with > > - link 0: dedicated corosync link > - link 1: corosync link over a bond with a problematic mode (such as > balance-rr or LACP with bond-lacp-rate slow) > > ? > In my tests, as long as the dedicated link 0 is completely online, it > doesn't matter if a bond runs into the failure scenario above (one of > the bonded NICs stops transmitting packets), corosync will just continue > using link 0. But as soon as link 0 goes down and the failure scenario > happens, the whole-cluster fence may happen. So should our > recommendation be the relatively strict "if you put corosync on a bond > (even if it is only a redundant link), use only active-backup or > LACP+bond-lacp-rate fast"? I'd say yes, the recommendation should be either dedicated link directly, or a bond as redundant link with active-backup or LACP+lacp-rate fast only. _______________________________________________ pve-devel mailing list pve-devel@lists.proxmox.com https://lists.proxmox.com/cgi-bin/mailman/listinfo/pve-devel