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 EE142977E8 for ; Tue, 5 Mar 2024 13:13:48 +0100 (CET) Received: from firstgate.proxmox.com (localhost [127.0.0.1]) by firstgate.proxmox.com (Proxmox) with ESMTP id D647975BF for ; Tue, 5 Mar 2024 13:13:48 +0100 (CET) Received: from proxmox-new.maurer-it.com (proxmox-new.maurer-it.com [94.136.29.106]) (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 for ; Tue, 5 Mar 2024 13:13:48 +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 E6E204881D for ; Tue, 5 Mar 2024 13:13:47 +0100 (CET) From: Christoph Heiss To: pve-devel@lists.proxmox.com Date: Tue, 5 Mar 2024 13:13:00 +0100 Message-ID: <20240305121338.264017-1-c.heiss@proxmox.com> X-Mailer: git-send-email 2.43.1 MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-SPAM-LEVEL: Spam detection results: 0 AWL 0.005 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 T_SCC_BODY_TEXT_LINE -0.01 - URIBL_BLOCKED 0.001 ADMINISTRATOR NOTICE: The query to URIBL was blocked. See http://wiki.apache.org/spamassassin/DnsBlocklists#dnsbl-block for more information. [proxmox.com] Subject: [pve-devel] [PATCH docs] local-zfs: mention `zfs_arc_max` clamping by the installer 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: Tue, 05 Mar 2024 12:13:49 -0000 This was forgotten to be updated when it changed it the installer and now reported in the forum [0] that the docs are a bit outdated in this regard. [0] https://forum.proxmox.com/threads/hat-proxmox-8-neue-zfs_arc_max-settings.142754/ Signed-off-by: Christoph Heiss --- local-zfs.adoc | 19 ++++++++++++------- 1 file changed, 12 insertions(+), 7 deletions(-) diff --git a/local-zfs.adoc b/local-zfs.adoc index a1a14e4..c977558 100644 --- a/local-zfs.adoc +++ b/local-zfs.adoc @@ -568,11 +568,16 @@ Limit ZFS Memory Usage ~~~~~~~~~~~~~~~~~~~~~~ ZFS uses '50 %' of the host memory for the **A**daptive **R**eplacement -**C**ache (ARC) by default. Allocating enough memory for the ARC is crucial for -IO performance, so reduce it with caution. As a general rule of thumb, allocate -at least +2 GiB Base + 1 GiB/TiB-Storage+. For example, if you have a pool with -+8 TiB+ of available storage space then you should use +10 GiB+ of memory for -the ARC. +**C**ache (ARC) by default. For new installations starting with {pve} 8.1, the +ARC usage limit will be set to '10 %' of the installed physical memory, clamped +to a maximum of +16 GiB+. This value is written to `/etc/modprobe.d/zfs.conf`. + +Allocating enough memory for the ARC is crucial for IO performance, so reduce it +with caution. As a general rule of thumb, allocate at least +2 GiB Base + 1 +GiB/TiB-Storage+. For example, if you have a pool with +8 TiB+ of available +storage space then you should use +10 GiB+ of memory for the ARC. + +ZFS also enforces a minimum value of +64 MiB+. You can change the ARC usage limit for the current boot (a reboot resets this change again) by writing to the +zfs_arc_max+ module parameter directly: @@ -581,8 +586,8 @@ change again) by writing to the +zfs_arc_max+ module parameter directly: echo "$[10 * 1024*1024*1024]" >/sys/module/zfs/parameters/zfs_arc_max ---- -To *permanently change* the ARC limits, add the following line to -`/etc/modprobe.d/zfs.conf`: +To *permanently change* the ARC limits, add (or change if already present) the +following line to `/etc/modprobe.d/zfs.conf`: -------- options zfs zfs_arc_max=8589934592 -- 2.43.1