From: "Fabian Grünbichler" <f.gruenbichler@proxmox.com>
To: Proxmox Backup Server development discussion
<pbs-devel@lists.proxmox.com>
Subject: Re: [pbs-devel] [PATCH v8 proxmox-backup 58/69] docs: add section describing change detection mode
Date: Tue, 04 Jun 2024 14:07:55 +0200 [thread overview]
Message-ID: <1717502521.11jolrj11q.astroid@yuna.none> (raw)
In-Reply-To: <20240528094303.309806-59-c.ebner@proxmox.com>
On May 28, 2024 11:42 am, Christian Ebner wrote:
> Describe the motivation and basic principle of the clients change
> detection mode and show an example invocation.
>
> Signed-off-by: Christian Ebner <c.ebner@proxmox.com>
> ---
> changes since version 7:
> - no changes
>
> changes since version 6:
> - add more information on metadata being compared
> - adapt and link from technical overview
>
> docs/backup-client.rst | 45 +++++++++++++++++++++++++++++++++++++
> docs/technical-overview.rst | 3 +++
> 2 files changed, 48 insertions(+)
>
> diff --git a/docs/backup-client.rst b/docs/backup-client.rst
> index 00a1abbb3..58fcd79f0 100644
> --- a/docs/backup-client.rst
> +++ b/docs/backup-client.rst
> @@ -280,6 +280,51 @@ Multiple paths can be excluded like this:
>
> # proxmox-backup-client backup.pxar:./linux --exclude=/usr --exclude=/rust
>
> +.. _client_change_detection_mode:
> +
> +Change Detection Mode
> +~~~~~~~~~~~~~~~~~~~~~
> +
> +File-based backups containing a lot of data can take a long time, as the default
> +behavior for the Proxmox backup client is to read all data and re-encode it.
read all data and encode it into a pxar archive.
> +The encoded stream is split into variable sized chunks for efficient
> +deduplication and based on the chunk digest a decision can be made whether a
I think I'd drop the efficient deduplication, the whole point of this
section is that it is not that efficient :-P
is split into variable sized chunks. For each chunk, a digest is
calculated and used to decide whether the chunk needs ..
> +given chunk needs to be uploaded or can be indexed without upload as it is
> +already available on the server (and therefore deduplicated). For some
> +use-cases, where files do not change frequently the full re-reading is not
> +feasible and undesired.
If the backed up files are largely unchanged, re-reading and then
deciding the corresponding chunks don't need to be uploaded at all (..
something something undesired ;))
> +
> +The backup clients `change-detection-mode` can be switched from default to
client's
> +`metadata` based detection to reduce limitations as described above, instructing
> +the client to avoid re-reading files with unchanged metadata whenever possible.
> +When using this mode, instead of the regular pxar archive, the backup snapshot
> +is stored into two separate files: the `mpxar` containing the archives metadata
archive's
> +and the `ppxar` containing a concatenation of the file contents. This splitting
> +allows for metadata lookups without the overhead of the file contents.
for efficient metadata lookups. ?
> +Using the `change-detection-mode` set to `data` allows to create the same split
> +archive as when using the `metadata` mode, but without using a previous
> +reference and therefore reencoding all file payloads.
this part should move below, since the next paragraphs describe the
metadata mode?
> +
> +When creating the backup archives, the current file metadata is compared to the
> +one looked up in the previous `mpxar` archive.
> +The metadata comparison includes file size, file type, ownership and permission
> +information acls and attributes and most importantly the files mtime, for
something here is missing (a comma?), and s/files/file's/
> +details see the :ref:`pxar metadata archive format <pxar-meta-format>`.
> +
> +If unchanged, the entry is cached for possible re-use of content chunks without
> +re-reading, by indexing the already present chunks containing the contents from
> +the previous backup snapshot. Since the file might only partially re-use chunks
> +(thereby introducing wasted space in the form of padding), the decision whether
> +to re-use or re-encode the currently cached entries is delegated to when enough
is delayed/postponed
> +information is available, comparing the possible padding a threshold value.
to a
> +
> +The following shows an example for the client invocation with the `metadata`
> +mode:
> +
> +.. code-block:: console
> +
> + # proxmox-backup-client backup.pxar:./linux --change-detection-mode=metadata
> +
> .. _client_encryption:
>
> Encryption
> diff --git a/docs/technical-overview.rst b/docs/technical-overview.rst
> index 89835a7cc..a8b1c7268 100644
> --- a/docs/technical-overview.rst
> +++ b/docs/technical-overview.rst
> @@ -28,6 +28,9 @@ which are not chunked, e.g. the client log), or one or more indexes
>
> When uploading an index, the client first has to read the source data, chunk it
> and send the data as chunks with their identifying checksum to the server.
> +When using the :ref:`change detection mode <change_detection_mode>` payload
> +chunks for unchanged files are reused from the previous snapshot, thereby not
> +reading the source data again.
>
> If there is a previous Snapshot in the backup group, the client can first
> download the chunk list of the previous Snapshot. If it detects a chunk that
> --
> 2.39.2
>
>
>
> _______________________________________________
> pbs-devel mailing list
> pbs-devel@lists.proxmox.com
> https://lists.proxmox.com/cgi-bin/mailman/listinfo/pbs-devel
>
>
>
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next prev parent reply other threads:[~2024-06-04 12:07 UTC|newest]
Thread overview: 101+ messages / expand[flat|nested] mbox.gz Atom feed top
2024-05-28 9:41 [pbs-devel] [PATCH v8 pxar proxmox-backup 00/69] fix #3174: improve file-level backup Christian Ebner
2024-05-28 9:41 ` [pbs-devel] [PATCH v8 pxar 01/69] decoder: factor out skip part from skip_entry Christian Ebner
2024-05-28 9:41 ` [pbs-devel] [PATCH v8 pxar 02/69] lib: add type for input/output variant differentiation Christian Ebner
2024-05-28 9:41 ` [pbs-devel] [PATCH v8 pxar 03/69] encoder: move to stack based state tracking Christian Ebner
2024-05-28 9:41 ` [pbs-devel] [PATCH v8 pxar 04/69] format/examples: add header type `PXAR_PAYLOAD_REF` Christian Ebner
2024-05-28 9:41 ` [pbs-devel] [PATCH v8 pxar 05/69] decoder: add method to read payload references Christian Ebner
2024-05-28 9:42 ` [pbs-devel] [PATCH v8 pxar 06/69] encoder: allow split output writer for archive creation Christian Ebner
2024-05-29 11:54 ` Dominik Csapak
2024-05-28 9:42 ` [pbs-devel] [PATCH v8 pxar 07/69] decoder/accessor: allow for split input stream variant Christian Ebner
2024-05-28 9:42 ` [pbs-devel] [PATCH v8 pxar 08/69] decoder: set payload input range when decoding via accessor Christian Ebner
2024-05-28 9:42 ` [pbs-devel] [PATCH v8 pxar 09/69] encoder: add payload reference capability Christian Ebner
2024-05-28 9:42 ` [pbs-devel] [PATCH v8 pxar 10/69] encoder: add payload position capability Christian Ebner
2024-05-28 9:42 ` [pbs-devel] [PATCH v8 pxar 11/69] encoder: add payload advance capability Christian Ebner
2024-05-28 9:42 ` [pbs-devel] [PATCH v8 pxar 12/69] encoder/format: finish payload stream with marker Christian Ebner
2024-05-28 9:42 ` [pbs-devel] [PATCH v8 pxar 13/69] format: add payload stream start marker Christian Ebner
2024-05-28 9:42 ` [pbs-devel] [PATCH v8 pxar 14/69] format/encoder/decoder: new pxar entry type `Version` Christian Ebner
2024-06-03 11:25 ` Fabian Grünbichler
2024-06-03 11:54 ` Christian Ebner
2024-06-03 12:10 ` Christian Ebner
2024-05-28 9:42 ` [pbs-devel] [PATCH v8 pxar 15/69] format/encoder/decoder: new pxar entry type `Prelude` Christian Ebner
2024-05-28 9:42 ` [pbs-devel] [PATCH v8 proxmox-backup 16/69] client: backup: factor out extension from backup target Christian Ebner
2024-05-28 9:42 ` [pbs-devel] [PATCH v8 proxmox-backup 17/69] api: datastore: refactor getting local chunk reader Christian Ebner
2024-05-28 9:42 ` [pbs-devel] [PATCH v8 proxmox-backup 18/69] client: pxar: switch to stack based encoder state Christian Ebner
2024-05-28 9:42 ` [pbs-devel] [PATCH v8 proxmox-backup 19/69] client: pxar: combine writers into struct Christian Ebner
2024-05-28 9:42 ` [pbs-devel] [PATCH v8 proxmox-backup 20/69] client: pxar: optionally split metadata and payload streams Christian Ebner
2024-05-28 9:42 ` [pbs-devel] [PATCH v8 proxmox-backup 21/69] client: helper: add helpers for creating reader instances Christian Ebner
2024-05-28 9:42 ` [pbs-devel] [PATCH v8 proxmox-backup 22/69] client: helper: add method for split archive name mapping Christian Ebner
2024-06-04 8:17 ` Fabian Grünbichler
2024-06-04 8:30 ` Christian Ebner
2024-05-28 9:42 ` [pbs-devel] [PATCH v8 proxmox-backup 23/69] client: tools: helper to check pxar filename extensions Christian Ebner
2024-05-28 9:42 ` [pbs-devel] [PATCH v8 proxmox-backup 24/69] client: restore: read payload from dedicated index Christian Ebner
2024-05-28 9:42 ` [pbs-devel] [PATCH v8 proxmox-backup 25/69] tools: cover extension for split pxar archives Christian Ebner
2024-05-28 9:42 ` [pbs-devel] [PATCH v8 proxmox-backup 26/69] restore: " Christian Ebner
2024-05-28 9:42 ` [pbs-devel] [PATCH v8 proxmox-backup 27/69] client: mount: make split pxar archives mountable Christian Ebner
2024-06-04 8:24 ` Fabian Grünbichler
2024-05-28 9:42 ` [pbs-devel] [PATCH v8 proxmox-backup 28/69] api: datastore: attach split archive payload chunk reader Christian Ebner
2024-06-04 8:26 ` Fabian Grünbichler
2024-05-28 9:42 ` [pbs-devel] [PATCH v8 proxmox-backup 29/69] catalog: shell: make split pxar archives accessible Christian Ebner
2024-05-28 9:42 ` [pbs-devel] [PATCH v8 proxmox-backup 30/69] www: cover metadata extension for pxar archives Christian Ebner
2024-05-28 9:42 ` [pbs-devel] [PATCH v8 proxmox-backup 31/69] file restore: factor out getting pxar reader Christian Ebner
2024-05-28 9:42 ` [pbs-devel] [PATCH v8 proxmox-backup 32/69] file restore: cover split metadata and payload archives Christian Ebner
2024-06-04 8:28 ` Fabian Grünbichler
2024-05-28 9:42 ` [pbs-devel] [PATCH v8 proxmox-backup 33/69] file restore: show more error context when extraction fails Christian Ebner
2024-05-28 9:42 ` [pbs-devel] [PATCH v8 proxmox-backup 34/69] pxar: add optional payload input for archive restore Christian Ebner
2024-06-03 13:23 ` Fabian Grünbichler
2024-05-28 9:42 ` [pbs-devel] [PATCH v8 proxmox-backup 35/69] pxar: cover listing for split archives Christian Ebner
2024-06-03 13:27 ` Fabian Grünbichler
2024-06-03 13:36 ` Christian Ebner
2024-06-03 14:54 ` Christian Ebner
2024-05-28 9:42 ` [pbs-devel] [PATCH v8 proxmox-backup 36/69] pxar: add more context to extraction error Christian Ebner
2024-05-28 9:42 ` [pbs-devel] [PATCH v8 proxmox-backup 37/69] client: pxar: include payload offset in entry listing Christian Ebner
2024-05-28 9:42 ` [pbs-devel] [PATCH v8 proxmox-backup 38/69] pxar: show padding in debug output on archive list Christian Ebner
2024-06-04 8:34 ` Fabian Grünbichler
2024-05-28 9:42 ` [pbs-devel] [PATCH v8 proxmox-backup 39/69] datastore: dynamic index: add method to get digest Christian Ebner
2024-05-28 9:42 ` [pbs-devel] [PATCH v8 proxmox-backup 40/69] client: pxar: helper for lookup of reusable dynamic entries Christian Ebner
2024-05-28 9:42 ` [pbs-devel] [PATCH v8 proxmox-backup 41/69] upload stream: implement reused chunk injector Christian Ebner
2024-06-04 8:50 ` Fabian Grünbichler
2024-06-04 8:58 ` Christian Ebner
2024-05-28 9:42 ` [pbs-devel] [PATCH v8 proxmox-backup 42/69] client: chunk stream: add struct to hold injection state Christian Ebner
2024-05-28 9:42 ` [pbs-devel] [PATCH v8 proxmox-backup 43/69] chunker: add method to reset chunker state Christian Ebner
2024-05-28 9:42 ` [pbs-devel] [PATCH v8 proxmox-backup 44/69] client: streams: add channels for dynamic entry injection Christian Ebner
2024-05-28 9:42 ` [pbs-devel] [PATCH v8 proxmox-backup 45/69] specs: add backup detection mode specification Christian Ebner
2024-05-28 9:42 ` [pbs-devel] [PATCH v8 proxmox-backup 46/69] client: implement prepare reference method Christian Ebner
2024-06-04 9:24 ` Fabian Grünbichler
2024-06-04 12:45 ` Christian Ebner
2024-05-28 9:42 ` [pbs-devel] [PATCH v8 proxmox-backup 47/69] client: pxar: add method for metadata comparison Christian Ebner
2024-05-28 9:42 ` [pbs-devel] [PATCH v8 proxmox-backup 48/69] pxar: caching: add look-ahead cache Christian Ebner
2024-06-04 9:35 ` Fabian Grünbichler
2024-06-04 13:58 ` Christian Ebner
2024-06-05 10:56 ` Christian Ebner
2024-05-28 9:42 ` [pbs-devel] [PATCH v8 proxmox-backup 49/69] client: pxar: refactor catalog encoding for directories Christian Ebner
2024-05-28 9:42 ` [pbs-devel] [PATCH v8 proxmox-backup 50/69] fix #3174: client: pxar: enable caching and meta comparison Christian Ebner
2024-06-04 11:50 ` Fabian Grünbichler
2024-05-28 9:42 ` [pbs-devel] [PATCH v8 proxmox-backup 51/69] client: backup writer: add injected chunk count to stats Christian Ebner
2024-05-28 9:42 ` [pbs-devel] [PATCH v8 proxmox-backup 52/69] pxar: create: keep track of reused chunks and files Christian Ebner
2024-05-28 9:42 ` [pbs-devel] [PATCH v8 proxmox-backup 53/69] pxar: create: show chunk injection stats debug output Christian Ebner
2024-05-28 9:42 ` [pbs-devel] [PATCH v8 proxmox-backup 54/69] client: pxar: add helper to handle optional preludes Christian Ebner
2024-06-04 11:55 ` Fabian Grünbichler
2024-05-28 9:42 ` [pbs-devel] [PATCH v8 proxmox-backup 55/69] client: pxar: opt encode cli exclude patterns as Prelude Christian Ebner
2024-05-28 9:42 ` [pbs-devel] [PATCH v8 proxmox-backup 56/69] pxar: ignore version and prelude entries in listing Christian Ebner
2024-06-04 8:39 ` Fabian Grünbichler
2024-06-04 8:48 ` Christian Ebner
2024-05-28 9:42 ` [pbs-devel] [PATCH v8 proxmox-backup 57/69] docs: file formats: describe split pxar archive file layout Christian Ebner
2024-05-28 9:42 ` [pbs-devel] [PATCH v8 proxmox-backup 58/69] docs: add section describing change detection mode Christian Ebner
2024-06-04 12:07 ` Fabian Grünbichler [this message]
2024-05-28 9:42 ` [pbs-devel] [PATCH v8 proxmox-backup 59/69] test-suite: add detection mode change benchmark Christian Ebner
2024-05-28 9:42 ` [pbs-devel] [PATCH v8 proxmox-backup 60/69] test-suite: Makefile: add debian package and related files Christian Ebner
2024-05-28 9:42 ` [pbs-devel] [PATCH v8 proxmox-backup 61/69] datastore: chunker: add Chunker trait Christian Ebner
2024-05-28 9:42 ` [pbs-devel] [PATCH v8 proxmox-backup 62/69] datastore: chunker: implement chunker for payload stream Christian Ebner
2024-05-28 9:42 ` [pbs-devel] [PATCH v8 proxmox-backup 63/69] client: chunk stream: switch payload stream chunker Christian Ebner
2024-05-28 9:42 ` [pbs-devel] [PATCH v8 proxmox-backup 64/69] client: pxar: allow to restore prelude to optional path Christian Ebner
2024-06-03 13:57 ` Fabian Grünbichler
2024-06-03 15:02 ` Christian Ebner
2024-05-28 9:42 ` [pbs-devel] [PATCH v8 proxmox-backup 65/69] client: pxar: add archive creation with reference test Christian Ebner
2024-05-28 9:43 ` [pbs-devel] [PATCH v8 proxmox-backup 66/69] client: tools: add helper to raise nofile rlimit Christian Ebner
2024-05-28 9:43 ` [pbs-devel] [PATCH v8 proxmox-backup 67/69] client: pxar: set cache limit based on " Christian Ebner
2024-05-28 9:43 ` [pbs-devel] [PATCH v8 proxmox-backup 68/69] chunker: tests: add regression tests for payload chunker Christian Ebner
2024-05-28 9:43 ` [pbs-devel] [PATCH v8 proxmox-backup 69/69] chunk stream: " Christian Ebner
2024-05-31 10:40 ` [pbs-devel] [PATCH v8 pxar proxmox-backup 00/69] fix #3174: improve file-level backup Dominik Csapak
2024-05-31 11:19 ` Christian Ebner
2024-06-05 8:51 ` [pbs-devel] partially-applied: " Fabian Grünbichler
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