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 313F71FF187 for ; Mon, 28 Jul 2025 18:15:25 +0200 (CEST) Received: from firstgate.proxmox.com (localhost [127.0.0.1]) by firstgate.proxmox.com (Proxmox) with ESMTP id 17CF138580; Mon, 28 Jul 2025 18:16:47 +0200 (CEST) Message-ID: <86841dab-96d5-403d-a91f-a69d17b716a7@proxmox.com> Date: Mon, 28 Jul 2025 18:16:12 +0200 MIME-Version: 1.0 User-Agent: Mozilla Thunderbird To: Proxmox VE development discussion , Friedrich Weber References: <20250725140312.250936-1-f.weber@proxmox.com> Content-Language: en-US From: Hannes Duerr In-Reply-To: <20250725140312.250936-1-f.weber@proxmox.com> X-Bm-Milter-Handled: 55990f41-d878-4baa-be0a-ee34c49e34d2 X-Bm-Transport-Timestamp: 1753719364089 X-SPAM-LEVEL: Spam detection results: 0 AWL 0.073 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 HTML_MESSAGE 0.001 HTML included in message 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. 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SPF_HELO_NONE 0.001 SPF: HELO does not publish an SPF Record SPF_PASS -0.001 SPF: sender matches SPF record X-Content-Filtered-By: Mailman/MimeDel 2.1.29 Subject: Re: [pve-devel] [PATCH docs v3] 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-Transfer-Encoding: 7bit Content-Type: text/plain; charset="us-ascii"; Format="flowed" Errors-To: pve-devel-bounces@lists.proxmox.com Sender: "pve-devel" On 7/25/25 4:03 PM, Friedrich Weber wrote: > +Corosync Over Bonds > +~~~~~~~~~~~~~~~~~~~ > + > +Using a xref:sysadmin_network_bond[bond] as a 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, and there are no other > +Corosync links available I thought it can also occur if the are still other Corosync links available? If i understand the next part correct you're even assuming it? > , some bond modes may cause a state of asymmetric > +connectivity where cluster nodes can only communicate with different subsets of > +other nodes. Affected are bond modes that provide load balancing, as these > +modes may still try to send out a subset of packets via the failed interface. > +In case of asymmetric connectivity, Corosync may not be able to form a stable > +quorum in the cluster. --- here > 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. > + > +We recommend at least one dedicated physical NIC for the primary Corosync link, > +see xref:pvecm_cluster_requirements[Requirements]. Bonds may be used as > +additional links for increased redundancy. To avoid fencing in the failure > +scenario outlined above, the following caveats apply whenever a bond is used > +for Corosync traffic: > + > +* We *advise against* using bond modes *balance-rr*, *balance-xor*, > + *balance-tlb*, or *balance-alb* for Corosync traffic. As explained above, > + they can cause asymmetric connectivity in certain failure scenarios. > + > +* *IEEE 802.3ad (LACP)*: This bond mode can cause asymmetric connectivity in > + certain failure scenarios as explained above, but it can recover from this > + state, as each side of the bond (Proxmox VE node and switch) can stop using a > + bonded interface if it has not received three LACPDUs in a row on it. > + However, with default settings, LACPDUs are only sent every 30 seconds, > + yielding a failover time of 90 seconds. This is too long, as nodes with HA > + resources will fence themselves already after roughly one minute without a > + stable quorum. If LACP bonds are used for corosync traffic, we recommend > + setting `bond-lacp-rate fast` *on the Proxmox VE node and the switch*! > + Setting this option on one side requests the other side to send an LACPDU > + every second. Setting this option on both sides can reduce the failover time > + in the scenario above to 3 seconds and thus prevent fencing. > + > +* Bond mode *active-backup* will not cause asymmetric connectivity in the > + failure scenario described above. The node whose bond experienced the failure > + may lose connection to the cluster and, if HA is enabled, fence itself. > + > Separate Cluster Network > ~~~~~~~~~~~~~~~~~~~~~~~~ > _______________________________________________ pve-devel mailing list pve-devel@lists.proxmox.com https://lists.proxmox.com/cgi-bin/mailman/listinfo/pve-devel