From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from gate001.proxmox.com (gate001.proxmox.com [45.144.208.40]) by lore.proxmox.com (Postfix) with ESMTPS id 4D4C31FF146 for ; Tue, 07 Jul 2026 16:33:53 +0200 (CEST) Received: from gate001.proxmox.com (localhost.localdomain [127.0.0.1]) by gate001.proxmox.com (Proxmox) with ESMTP id CE7442143D; Tue, 07 Jul 2026 16:33:34 +0200 (CEST) From: Lukas Sichert To: pve-devel@lists.proxmox.com Subject: [PATCH docs v8 5/5] fix #7339: lvm: document discard option Date: Tue, 7 Jul 2026 16:32:48 +0200 Message-ID: <20260707143252.101757-6-l.sichert@proxmox.com> X-Mailer: git-send-email 2.47.3 In-Reply-To: <20260707143252.101757-1-l.sichert@proxmox.com> References: <20260707143252.101757-1-l.sichert@proxmox.com> MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-Bm-Milter-Handled: 55990f41-d878-4baa-be0a-ee34c49e34d2 X-Bm-Transport-Timestamp: 1783434773260 X-SPAM-LEVEL: Spam detection results: 0 AWL 0.000 Adjusted score from AWL reputation of From: address DMARC_MISSING 0.1 Missing DMARC policy KAM_DMARC_STATUS 0.01 Test Rule for DKIM or SPF Failure with Strict Alignment (newer systems) 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: F44XIBETR6J5KRLKHEL7LEO67CANV5I4 X-Message-ID-Hash: F44XIBETR6J5KRLKHEL7LEO67CANV5I4 X-MailFrom: l.sichert@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 CC: Lukas Sichert X-Mailman-Version: 3.3.10 Precedence: list List-Id: Proxmox VE development discussion List-Help: List-Owner: List-Post: List-Subscribe: List-Unsubscribe: Document the new `on-volume-remove` property for LVM storage and its initial `discard` action. Also update the `saferemove` description to match the range-based zero-out worker and avoid referring to the old command-specific implementation details. Signed-off-by: Lukas Sichert Link: bugzilla.proxmox.com/show_bug.cgi?id=7339 --- pve-storage-lvm.adoc | 34 +++++++++++++++++++++++++++------- 1 file changed, 27 insertions(+), 7 deletions(-) diff --git a/pve-storage-lvm.adoc b/pve-storage-lvm.adoc index ba78663..3ddb26c 100644 --- a/pve-storage-lvm.adoc +++ b/pve-storage-lvm.adoc @@ -44,18 +44,39 @@ accessed by other LVs created later (which happen to be assigned the same physical extents). This is a costly operation, but may be required as a security measure in certain environments. + -Storage devices that support the "write zeroes" operation will use `blkdiscard` -to zero blocks. Otherwise, a fallback to `cstream` is performed. +Storage devices that support the "write zeroes" operation use it to zero blocks. +Otherwise, zeroes are written manually. The volume is processed range by range, +according to `saferemove-stepsize`. + +`on-volume-remove`:: + +Configure additional actions to run before an LV is removed. ++ +Set `discard=1` to issue discard (TRIM) requests for the LV's blocks before the +LV is removed, so thin-provisioned backing storage, such as a SAN LUN, can +reclaim space the LV occupied. This is called "Discard Removed Volumes" +in the web UI. Discard is rejected if any backing device in the +LV's volume group is detected as not supporting it. ++ +If wiping or discarding fails, the renamed `del-*` LV is kept and renamed to +`failed--del-*`, so one can inspect it, retry cleanup manually, or remove +it explicitly. ++ +If `saferemove` and `discard` are both enabled, the LV is processed range by +range: one range is zeroed out and then discarded before continuing with the +next range. This avoids allocating the whole LV with zeroes on thin-provisioned +backing storage before the space can be reclaimed again. `saferemove-stepsize`:: -Wipe step size in MiB (`blkdiscard -p` parameter value), capped to the maximum -step size supported by the underlying storage. Up to 32 MiB (maximum) by -default. +Wipe step size in MiB, capped to the maximum step size supported by the +underlying storage. Up to 32 MiB (maximum) by default. `saferemove_throughput`:: -Wipe throughput (`cstream -t` parameter value), up to 10 MiB/s by default. +Limits wipe throughput. If the backing storage supports the "write zeroes" +operation, throughput is unlimited by default. Otherwise, manually written +zeroes are limited to 10 MiB/s by default. `snapshot-as-volume-chain`:: @@ -150,4 +171,3 @@ See Also endif::wiki[] - -- 2.47.3