From 2c12c2b1d5e66b73d09298f07b554c8fcd125424 Mon Sep 17 00:00:00 2001 From: Aaron Lauterer Date: Mon, 20 Jan 2025 15:32:57 +0100 Subject: [PATCH] qm, vzdump: add notes regarding backups of windows and VSS VSS in windows guests with additional backup software in the guest can cause problems. By now the guest agent does support to use a different VSS option. This way, one can switch to one that does not interfere with other backup solutions. Mention it in the docs and link to the wiki article that explains it. Signed-off-by: Aaron Lauterer Reviewed-by: Alexander Zeidler --- qm.adoc | 15 ++++++++++----- vzdump.adoc | 4 ++++ 2 files changed, 14 insertions(+), 5 deletions(-) diff --git a/qm.adoc b/qm.adoc index 4bb8f2c..40caaa3 100644 --- a/qm.adoc +++ b/qm.adoc @@ -1355,14 +1355,19 @@ that calling 'fs-freeze' with some SQL Servers triggers VSS to call the SQL Writer VSS module in a mode that breaks the SQL Server backup chain for differential backups. -For such setups you can configure {pve} to not issue a freeze-and-thaw cycle on +There are two options on how to handle such a situation. + +1. Configure the QEMU Guest Agent to use a different VSS variant that does not +interfere with other VSS users. The https://pve.proxmox.com/wiki/VM_Backup_Consistency[{pve} wiki] +has more details. +2. Alternatively, 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`. This can also be done via the GUI with the 'Freeze/thaw guest filesystems on backup for consistency' option. - -IMPORTANT: Disabling this option can potentially lead to backups with inconsistent -filesystems and should therefore only be disabled if you know what you are -doing. ++ +IMPORTANT: Disabling this option can potentially lead to backups with +inconsistent filesystems. Therefore, adapting the QEMU Guest Agent +configuration in the guest is the preferred option. Troubleshooting ^^^^^^^^^^^^^^^ diff --git a/vzdump.adoc b/vzdump.adoc index aecb353..d0c26d9 100644 --- a/vzdump.adoc +++ b/vzdump.adoc @@ -84,6 +84,10 @@ backup, in which data blocks are copied while the VM is running. If the guest agent is enabled (`agent: 1`) and running, it calls `guest-fsfreeze-freeze` and `guest-fsfreeze-thaw` to improve consistency. ++ +NOTE: On Windows guests it is necessary to configure the guest agent if another +backup software is used within the guest. See xref:qm_qga_fsfreeze[Freeze & Thaw] +in the guest agent section for more details. A technical overview of the {pve} live backup for QemuServer can be found online