From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from firstgate.proxmox.com (firstgate.proxmox.com [212.224.123.68]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature RSA-PSS (2048 bits)) (No client certificate requested) by lists.proxmox.com (Postfix) with ESMTPS id 323826B264 for ; Thu, 18 Feb 2021 11:39:24 +0100 (CET) Received: from firstgate.proxmox.com (localhost [127.0.0.1]) by firstgate.proxmox.com (Proxmox) with ESMTP id 30500C0EF for ; Thu, 18 Feb 2021 11:39:24 +0100 (CET) Received: from proxmox-new.maurer-it.com (proxmox-new.maurer-it.com [212.186.127.180]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature RSA-PSS (2048 bits)) (No client certificate requested) by firstgate.proxmox.com (Proxmox) with ESMTPS id 7104CC0E7 for ; Thu, 18 Feb 2021 11:39:23 +0100 (CET) Received: from proxmox-new.maurer-it.com (localhost.localdomain [127.0.0.1]) by proxmox-new.maurer-it.com (Proxmox) with ESMTP id 3DFA341BB3 for ; Thu, 18 Feb 2021 11:39:23 +0100 (CET) From: Dylan Whyte To: pve-devel@lists.proxmox.com Date: Thu, 18 Feb 2021 11:39:10 +0100 Message-Id: <20210218103910.21127-2-d.whyte@proxmox.com> X-Mailer: git-send-email 2.20.1 In-Reply-To: <20210218103910.21127-1-d.whyte@proxmox.com> References: <20210218103910.21127-1-d.whyte@proxmox.com> MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-SPAM-LEVEL: Spam detection results: 0 AWL 0.017 Adjusted score from AWL reputation of From: address KAM_DMARC_STATUS 0.01 Test Rule for DKIM or SPF Failure with Strict Alignment KAM_SHORT 0.001 Use of a URL Shortener for very short URL RCVD_IN_DNSWL_MED -2.3 Sender listed at https://www.dnswl.org/, medium trust 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 v2 pve-docs 2/2] ceph: add explanation on the pg autoscaler 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: , X-List-Received-Date: Thu, 18 Feb 2021 10:39:24 -0000 Signed-off-by: Alwin Antreich edited-by: Dylan Whyte --- v1->v2: * minor language fixup pveceph.adoc | 36 ++++++++++++++++++++++++++++++++++++ 1 file changed, 36 insertions(+) diff --git a/pveceph.adoc b/pveceph.adoc index 9253613..9ef268b 100644 --- a/pveceph.adoc +++ b/pveceph.adoc @@ -540,6 +540,42 @@ pveceph pool destroy NOTE: Deleting the data of a pool is a background task and can take some time. You will notice that the data usage in the cluster is decreasing. + +PG Autoscaler +~~~~~~~~~~~~~ + +The PG autoscaler allows the cluster to consider the amount of (expected) data +stored in each pool and to choose the appropriate pg_num values automatically. + +You may need to activate the PG autoscaler module before adjustments can take +effect. +[source,bash] +---- +ceph mgr module enable pg_autoscaler +---- + +The autoscaler is configured on a per pool basis and has the following modes: + +[horizontal] +warn:: A health warning is issued if the suggested `pg_num` value differs too +much from the current value. +on:: The `pg_num` is adjusted automatically with no need for any manual +interaction. +off:: No automatic `pg_num` adjustments are made, and no warning will be issued +if the PG count is far from optimal. + +The scaling factor can be adjusted to facilitate future data storage, with the +`target_size`, `target_size_ratio` and the `pg_num_min` options. + +WARNING: By default, the autoscaler considers tuning the PG count of a pool if +it is off by a factor of 3. This will lead to a considerable shift in data +placement and might introduce a high load on the cluster. + +You can find a more in-depth introduction to the PG autoscaler on Ceph's Blog - +https://ceph.io/rados/new-in-nautilus-pg-merging-and-autotuning/[New in +Nautilus: PG merging and autotuning]. + + [[pve_ceph_device_classes]] Ceph CRUSH & device classes --------------------------- -- 2.20.1