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 B6743942FC for ; Thu, 23 Feb 2023 12:34:54 +0100 (CET) Received: from firstgate.proxmox.com (localhost [127.0.0.1]) by firstgate.proxmox.com (Proxmox) with ESMTP id 943FD24059 for ; Thu, 23 Feb 2023 12:34:24 +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 ; Thu, 23 Feb 2023 12:34:23 +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 851AA48310 for ; Thu, 23 Feb 2023 12:34:23 +0100 (CET) Message-ID: Date: Thu, 23 Feb 2023 12:34:22 +0100 MIME-Version: 1.0 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:110.0) Gecko/20100101 Thunderbird/110.0 Content-Language: de-AT, en-GB To: Proxmox VE development discussion , Christoph Heiss References: <20230201125918.372665-1-c.heiss@proxmox.com> <20230201125918.372665-4-c.heiss@proxmox.com> From: Thomas Lamprecht In-Reply-To: <20230201125918.372665-4-c.heiss@proxmox.com> Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit X-SPAM-LEVEL: Spam detection results: 0 AWL -0.000 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 NICE_REPLY_A -0.102 Looks like a legit reply (A) SPF_HELO_NONE 0.001 SPF: HELO does not publish an SPF Record SPF_PASS -0.001 SPF: sender matches SPF record Subject: Re: [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: Thu, 23 Feb 2023 11:34:54 -0000 Am 01/02/2023 um 13:59 schrieb Christoph Heiss: > 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 > +^^^^^^^^^^^^^^^^^^^^^^ Would title case this and add "on Backup", i.e.: Filesystem Freeze & Thaw on Backup > + > +By default, VM filesystems are synced via the 'fs-freeze' command when a backup I know we're already in the section, but it might help to remind user s/command/QEMU Guest Agent Command/ > +is performed, to provide consistency. On Windows guests, this calls into the VSS > +(volume shadow copy) subsystem. I'd either move the last sentence to the next paragraph or also mention how it's done in Linux, as otherwise this IMO reads as it has been put slightly out of place. > + > +There might be cases where this needs to be disabled, e.g. when running as per our technical writing style guide (see intranet wiki) s/e.g./for example/ > +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. I'd reword this a bit, maybe something a long the lines of: "Some applications handle consistent backups themselves by hooking into the Windows VSS layer, a fs-freeze might then interfere with that. For example calling fs-freeze whit some SQL Servers triggers VSS to call the SQL Writer VSS module in a mode that breaks the SQL backup chain for differential backups. For such setups you can configure {pve} to not issue a freeze and thaw cycle on backup by setting the `freeze-fs-on-backup` qga option to `0`, which can be also done via the web UI." Below might be obsolete if (something like) above is adopted, so just commenting two minor nits for completeness sake: > + > +This behavior can be turned off using the 'Freeze/thaw filesystems on backup > +for consistency' option. With this option disabled, {pve} will skip the s/skip/skip issuing/ > +'fs-freeze' and 'fs-thaw' commands when running backup jobs. s/commands/QGA commands/ > + > +NOTE: Disabling this option can potentially lead to backups with inconsistent > +filesystems and should therefore only be changed if you know what you are s/changed/disabled/ > +doing. > + > Troubleshooting > ^^^^^^^^^^^^^^^ >