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 299C591568 for ; Wed, 1 Feb 2023 13:59:26 +0100 (CET) Received: from firstgate.proxmox.com (localhost [127.0.0.1]) by firstgate.proxmox.com (Proxmox) with ESMTP id 0E5FE2FB7E for ; Wed, 1 Feb 2023 13:59:26 +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 ; Wed, 1 Feb 2023 13:59:24 +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 A79ED45A25 for ; Wed, 1 Feb 2023 13:59:24 +0100 (CET) From: Christoph Heiss To: pve-devel@lists.proxmox.com Date: Wed, 1 Feb 2023 13:59:18 +0100 Message-Id: <20230201125918.372665-4-c.heiss@proxmox.com> X-Mailer: git-send-email 2.39.1 In-Reply-To: <20230201125918.372665-1-c.heiss@proxmox.com> References: <20230201125918.372665-1-c.heiss@proxmox.com> MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-SPAM-LEVEL: Spam detection results: 0 AWL -0.153 Adjusted score from AWL reputation of From: address BAYES_00 -1.9 Bayes spam probability is 0 to 1% 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 3/3] qm: Add section explaining fs-freeze/thaw QGA option 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: Wed, 01 Feb 2023 12:59:26 -0000 Signed-off-by: Christoph Heiss --- qm.adoc | 20 ++++++++++++++++++++ 1 file changed, 20 insertions(+) diff --git a/qm.adoc b/qm.adoc index 8a49283..f029ceb 100644 --- a/qm.adoc +++ b/qm.adoc @@ -1061,6 +1061,26 @@ operations that have the potential to write out zeros to the storage: On a thin provisioned storage, this can help to free up unused space. +Filesystem freeze/thaw +^^^^^^^^^^^^^^^^^^^^^^ + +By default, VM filesystems are synced via the 'fs-freeze' command when a backup +is performed, to provide consistency. On Windows guests, this calls into the VSS +(volume shadow copy) subsystem. + +There might be cases where this needs to be disabled, e.g. when running +applications which hook into the Windows VSS subsystem themselves. This has +been observed to be necessary when running SQL Server, which otherwise might +break its own differential backup mode. + +This behavior can be turned off using the 'Freeze/thaw filesystems on backup +for consistency' option. With this option disabled, {pve} will skip the +'fs-freeze' and 'fs-thaw' commands when running backup jobs. + +NOTE: Disabling this option can potentially lead to backups with inconsistent +filesystems and should therefore only be changed if you know what you are +doing. + Troubleshooting ^^^^^^^^^^^^^^^ -- 2.39.1