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 0F44D1FF139 for ; Tue, 24 Feb 2026 11:53:58 +0100 (CET) Received: from firstgate.proxmox.com (localhost [127.0.0.1]) by firstgate.proxmox.com (Proxmox) with ESMTP id 1E8F84CF7; Tue, 24 Feb 2026 11:54:46 +0100 (CET) From: Maximiliano Sandoval To: pve-devel@lists.proxmox.com Subject: [PATCH docs 1/2] local-zfs: Rephrase ARC limit Date: Tue, 24 Feb 2026 11:54:33 +0100 Message-ID: <20260224105435.184325-2-m.sandoval@proxmox.com> X-Mailer: git-send-email 2.47.3 In-Reply-To: <20260224105435.184325-1-m.sandoval@proxmox.com> References: <20260224105435.184325-1-m.sandoval@proxmox.com> MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-Bm-Milter-Handled: 55990f41-d878-4baa-be0a-ee34c49e34d2 X-Bm-Transport-Timestamp: 1771930460582 X-SPAM-LEVEL: Spam detection results: 0 AWL -0.977 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 1.179 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 0.717 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 0.236 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 Message-ID-Hash: 7UZQOTHIHJO52O7XDA7EN4I7WFS4RQFT X-Message-ID-Hash: 7UZQOTHIHJO52O7XDA7EN4I7WFS4RQFT X-MailFrom: m.sandoval@proxmox.com X-Mailman-Rule-Misses: dmarc-mitigation; no-senders; approved; loop; banned-address; emergency; member-moderation; nonmember-moderation; administrivia; implicit-dest; max-recipients; max-size; news-moderation; no-subject; digests; suspicious-header X-Mailman-Version: 3.3.10 Precedence: list List-Id: Proxmox VE development discussion List-Help: List-Owner: List-Post: List-Subscribe: List-Unsubscribe: We rephrase the current section putting more emphasis on the current state of things given than Proxmox VE 8.1 was released over two years ago. This also frames the problem for pre-existing setups in its own paragraph. Signed-off-by: Maximiliano Sandoval --- local-zfs.adoc | 11 +++++++---- 1 file changed, 7 insertions(+), 4 deletions(-) diff --git a/local-zfs.adoc b/local-zfs.adoc index 4f20d00..12506d1 100644 --- a/local-zfs.adoc +++ b/local-zfs.adoc @@ -586,10 +586,13 @@ configured for the root user. Limit ZFS Memory Usage ~~~~~~~~~~~~~~~~~~~~~~ -ZFS uses '50 %' of the host memory for the **A**daptive **R**eplacement -**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`. +ZFS uses '10 %' of the host memory, clamped to a maximum of +16 GiB+, for the +**A**daptive **R**eplacement **C**ache (ARC) by default. This value is written +to `/etc/modprobe.d/zfs.conf` during installation. + +Before {pve} 8.1, the ARC usage limit was set to '50 %' without clamping it to a +maximum size. For existing installations that predate {pve} 8.1, manual steps +would have to be performed in order to lower the usage limit as described below. 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 -- 2.47.3