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 24E3094326 for ; Thu, 23 Feb 2023 13:10:23 +0100 (CET) Received: from firstgate.proxmox.com (localhost [127.0.0.1]) by firstgate.proxmox.com (Proxmox) with ESMTP id 018D5243E5 for ; Thu, 23 Feb 2023 13:10:23 +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 13:10:22 +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 11C4F4830F for ; Thu, 23 Feb 2023 13:10:22 +0100 (CET) Date: Thu, 23 Feb 2023 13:10:20 +0100 From: Christoph Heiss To: Thomas Lamprecht Cc: Proxmox VE development discussion Message-ID: <20230223121020.vaaekjv7chjemyqd@maui.proxmox.com> References: <20230201125918.372665-1-c.heiss@proxmox.com> <20230201125918.372665-4-c.heiss@proxmox.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: X-SPAM-LEVEL: Spam detection results: 0 AWL -0.094 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: 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 12:10:23 -0000 Thanks again, I'll incorporate your suggestions below as appriopriate for the next spin! On Thu, Feb 23, 2023 at 12:34:22PM +0100, Thomas Lamprecht wrote: > 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 > > ^^^^^^^^^^^^^^^ > > >