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 46D3975AD6 for ; Thu, 22 Apr 2021 14:21:38 +0200 (CEST) Received: from firstgate.proxmox.com (localhost [127.0.0.1]) by firstgate.proxmox.com (Proxmox) with ESMTP id 3B2171BD2F for ; Thu, 22 Apr 2021 14:21:38 +0200 (CEST) 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) server-digest SHA256) (No client certificate requested) by firstgate.proxmox.com (Proxmox) with ESMTPS id C1ACE1BD19 for ; Thu, 22 Apr 2021 14:21:36 +0200 (CEST) Received: from proxmox-new.maurer-it.com (localhost.localdomain [127.0.0.1]) by proxmox-new.maurer-it.com (Proxmox) with ESMTP id 9BC194627B for ; Thu, 22 Apr 2021 14:21:36 +0200 (CEST) From: Stefan Reiter To: pve-devel@lists.proxmox.com Date: Thu, 22 Apr 2021 14:21:27 +0200 Message-Id: <20210422122128.26198-1-s.reiter@proxmox.com> X-Mailer: git-send-email 2.20.1 MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-SPAM-LEVEL: Spam detection results: 0 AWL 0.035 Adjusted score from AWL reputation of From: address 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 v2 docs 1/2] vzdump: add section about live-restore 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, 22 Apr 2021 12:21:38 -0000 Signed-off-by: Stefan Reiter Reviewed-by: Dylan Whyte --- v2: * Incorporate Dylan's review + R-b Agreed with all suggestions, for both patches :) vzdump.adoc | 28 ++++++++++++++++++++++++++++ 1 file changed, 28 insertions(+) diff --git a/vzdump.adoc b/vzdump.adoc index 9453684..b8ea081 100644 --- a/vzdump.adoc +++ b/vzdump.adoc @@ -337,6 +337,34 @@ per configured storage, this can be done with: # pvesm set STORAGEID --bwlimit restore=KIBs ---- +Live-Restore +~~~~~~~~~~~~ + +Restoring a large backup can take a long time, in which a guest is still +unavailable. For VM backups stored on a Proxmox Backup Server, this wait +time can be mitigated using the live-restore option. + +Enabling live-restore via either the checkbox in the GUI or the `--live-restore` +argument of `qmrestore` causes the VM to start as soon as the restore +begins. Data is copied in the background, prioritizing chunks that the VM is +actively accessing. + +Note that this comes with two caveats: + +* During live-restore, the VM will operate with limited disk read speeds, as + data has to be loaded from the backup server (once loaded, it is immediately + available on the destination storage however, so accessing data twice only + incurs the penalty the first time). Write speeds are largely unaffected. +* If the live-restore fails for any reason, the VM will be left in an + undefined state - that is, not all data might have been copied from the + backup, and it is _most likely_ not possible to keep any data that was written + during the failed restore operation. + +This mode of operation is especially useful for large VMs, where only a small +amount of data is required for initial operation, e.g. web servers - once the OS +and necessary services have been started, the VM is operational, while the +background task continues copying seldomly used data. + [[vzdump_configuration]] Configuration ------------- -- 2.20.1