From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from firstgate.proxmox.com (firstgate.proxmox.com [212.224.123.68]) by lore.proxmox.com (Postfix) with ESMTPS id E447320EC8A for ; Mon, 29 Apr 2024 14:11:18 +0200 (CEST) Received: from firstgate.proxmox.com (localhost [127.0.0.1]) by firstgate.proxmox.com (Proxmox) with ESMTP id 46FBAF2A3; Mon, 29 Apr 2024 14:11:21 +0200 (CEST) From: Christian Ebner To: pbs-devel@lists.proxmox.com Date: Mon, 29 Apr 2024 14:10:04 +0200 Message-Id: <20240429121102.315059-1-c.ebner@proxmox.com> X-Mailer: git-send-email 2.39.2 MIME-Version: 1.0 X-SPAM-LEVEL: Spam detection results: 0 AWL 0.030 Adjusted score from AWL reputation of From: address BAYES_00 -1.9 Bayes spam probability is 0 to 1% DMARC_MISSING 0.1 Missing DMARC policy 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: [pbs-devel] [PATCH v4 pxar proxmox-backup 00/58] fix #3174: improve file-level backup X-BeenThere: pbs-devel@lists.proxmox.com X-Mailman-Version: 2.1.29 Precedence: list List-Id: Proxmox Backup Server development discussion List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Reply-To: Proxmox Backup Server development discussion Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Errors-To: pbs-devel-bounces@lists.proxmox.com Sender: "pbs-devel" A big thank you to Dietmar and Fabian for the review of the previous version and Fabian for extensive testing and help during debugging. This series of patches implements an metadata based file change detection mechanism for improved pxar file level backup creation speed for unchanged files. The chosen approach is to split pxar archives on creation via the proxmox-backup-client into two separate data and upload streams, one exclusive for regular file payloads, the other one for the rest of the pxar archive, which is mostly metadata. On consecutive runs, the metadata archive of the previous backup run, which is limited in size and therefore rapidly accessed is used to lookup and compare the metadata for entries to encode. This assumes that the connection speed to the Proxmox Backup Server is sufficiently fast, allowing the download and chaching of the chunks for that index. Changes to regular files are detected by comparing all of the files metadata object, including mtime, acls, ecc. If no changes are detected, the previous payload index is used to lookup chunks to possibly re-use in the payload stream of the new archive. In order to reduce possible chunk fragmentation, the decision whether to reuse or reencode a file payload is deferred until enough information is gathered by adding entries to a look-ahead cache. If the padding introduced by reusing chunks falls below a threshold, the entries are referenced, the chunks are reused and injected into the pxar payload upload stream, otherwise they are discated and the files encoded regularly. The following lists the most notable changes included in this series since the version 3: - Rework the whole reused chunk injection and accounting logic and use lockless async `mpsc::channel`s instead of `Arc>>`. - Reworked lookahead caching logic to use payload ranges and check for possible range continuation instead of looking up the reusable dynamic entries immediately in case of a reusable entry chain. This also avoids edge cases not covered in the previous version of the patch series. This current version therefore tends to reencode small files more aggressively, since they might introduce additional unwanted paddings. - Correctly cover also hardlinks for the reuse logic, avoiding to reencode these entries. - Add additional dedicatet chunker implementation for payload data stream, allowing the archiver to suggest boundaries to the chunker to reduce padding for reused chunks. - Add additional `change-detection-mode=data`, in order to allow creating split archives with fully reencoded payload data. - Add additional payload input readers for pxar accessor type implementations where needed. - Add additional consistency check in pxar encoder when dropping state or encoder instance. - CliParams was renamed to the more opaque Prelude, since the pxar archive does not care about its contents and this might be extended to store other information about the archive as well. - Add missing proxmox-file-restore for split archives and fix restore of tar/zip archives via WebUI. This is handled by the same decoder logic, and needed an updated payload input content range to read the data from the correct location in the payload data archive. - Additional refactoring to use the pxar reader helpers where possible. Still missing are the advanced usage of the prelude (currently only dumping the content is possible) and regression tests. Since the patches changed significalty in content and ordering, no per-patch changelog was created for this series. Patches 13 and 14 are to be applied to the pxar repository only after patch 49 in the series, for the patches to compile in a sequential chain. The following lists the most notable changes included in this series since the version 2: - many bugfixes regarding incorrect archive encoding by wrong offset generation, adding additional sanity checks and rather fail on encoding than produce an incorrectly encoded archive - different approach for deciding whether to reuse or reencode the entries. Previously, the entries have been encoded when a cached payload size threshold was reached. Now, the padding introduced by reusable chunks is tracked, and only if the padding does not exceed the set threshold, the entries are reused. This reduces the possible padding, at the cost of reencoding more entries. Also avoids to re-use chunks which have now large padding holes because of moved/removed files contained within. - added headers for metadata archive and payload file - added documentation An invocation of a backup run with this patches now is: ```bash proxmox-backup-client backup