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 23C991FF15C for ; Fri, 27 Jun 2025 15:45:07 +0200 (CEST) Received: from firstgate.proxmox.com (localhost [127.0.0.1]) by firstgate.proxmox.com (Proxmox) with ESMTP id 37C5515B96; Fri, 27 Jun 2025 15:45:29 +0200 (CEST) From: Aaron Lauterer To: pve-devel@lists.proxmox.com Date: Fri, 27 Jun 2025 15:44:52 +0200 Message-Id: <20250627134455.2065020-5-a.lauterer@proxmox.com> X-Mailer: git-send-email 2.39.5 In-Reply-To: <20250627134455.2065020-1-a.lauterer@proxmox.com> References: <20250627134455.2065020-1-a.lauterer@proxmox.com> MIME-Version: 1.0 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% DMARC_MISSING 0.1 Missing DMARC policy KAM_DMARC_STATUS 0.01 Test Rule for DKIM or SPF Failure with Strict Alignment SPF_HELO_NONE 0.001 SPF: HELO does not publish an SPF Record SPF_PASS -0.001 SPF: sender matches SPF record Subject: [pve-devel] [PATCH docs v2 4/5] pvecm: extend cluster Requirements 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" by expanding on best practices with background information as to how and why. Signed-off-by: Aaron Lauterer --- Notes: changes since: v1: * rephrase and reformat recommendations for additional corosync links pvecm.adoc | 26 ++++++++++++++++++++++++-- 1 file changed, 24 insertions(+), 2 deletions(-) diff --git a/pvecm.adoc b/pvecm.adoc index 3b9cfc4..d649e26 100644 --- a/pvecm.adoc +++ b/pvecm.adoc @@ -68,9 +68,31 @@ Requirements * If you are interested in High Availability, you need to have at least three nodes for reliable quorum. All nodes should have the same version. ++ +NOTE: For smaller 2-node clusters, the xref:_corosync_external_vote_support[QDevice] +can be used to provide a 3rd vote. -* We recommend a dedicated NIC for the cluster traffic, especially if - you use shared storage. +* We recommend a dedicated physical NIC for the cluster traffic. ++ +NOTE: The {pve} cluster communication uses the Corosync protocol. It needs consistent +low latency but not a lot of bandwidth. A dedicated 1 Gbit NIC is enough in +most situations. It helps to avoid situations where other services can use up +all the available bandwidth. Which in turn would increase the latency for the +Corosync packets. + +* Additional links for cluster traffic offers redundancy in case the dedicated +network is down. ++ +NOTE: Corosync supports up to 8 links. ++ +NOTE: To ensure reliable Corosync redundancy, it is essential to have at least +another link on a different physical network. This enables Corosync to keep the +cluster communication alive should the dedicated network be down. ++ +NOTE: A single link backed by a bond is not enough to provide Corosync +redundancy. When a bonded interface fails and Corosync cannot fall back to +another link, it can lead to asymmetric communication in the cluster, which in +turn can lead to the cluster losing quorum. * The root password of a cluster node is required for adding nodes. -- 2.39.5 _______________________________________________ pve-devel mailing list pve-devel@lists.proxmox.com https://lists.proxmox.com/cgi-bin/mailman/listinfo/pve-devel