From: Matthias Heiserer <m.heiserer@proxmox.com>
To: Proxmox Backup Server development discussion
<pbs-devel@lists.proxmox.com>,
Dominik Csapak <d.csapak@proxmox.com>
Subject: Re: [pbs-devel] [PATCH proxmox-backup v2 4/5] docs: add documentation about the 'sync-level' tuning
Date: Mon, 10 Oct 2022 09:54:10 +0200 [thread overview]
Message-ID: <293c5b4f-6f22-511a-a367-38411f677a73@proxmox.com> (raw)
In-Reply-To: <20221007115449.3562604-5-d.csapak@proxmox.com>
On 07.10.2022 13:54, Dominik Csapak wrote:
> Signed-off-by: Dominik Csapak <d.csapak@proxmox.com>
> ---
> docs/storage.rst | 36 ++++++++++++++++++++++++++++++++++++
> 1 file changed, 36 insertions(+)
>
> diff --git a/docs/storage.rst b/docs/storage.rst
> index 1909bd84..d7e19ec1 100644
> --- a/docs/storage.rst
> +++ b/docs/storage.rst
> @@ -338,3 +338,39 @@ and only available on the CLI:
>
> # proxmox-backup-manager datastore update <storename> --tuning 'chunk-order=none'
>
> +* ``sync-level``: Datastore fsync level:
> +
> + You can set the level of syncing on the datastore for chunks, which influences
> + the crash resistancy of backups in case of a powerloss or hard shutoff.
> + There are currently three levels:
> +
> + - `none` (default): Does not do any syncing when writing chunks. This is fast
> + and normally ok, since the kernel eventually flushes writes onto the disk.
> + The kernel sysctls `dirty_expire_centisecs` and `dirty_writeback_centisecs`
> + are used to tune that behaviour, while the default is to flush old data
> + after ~30s.
> +
> + - `filesystem` : This triggers a ``syncfs(2)`` after a backup, but before
> + the task returns `OK`. This way it is ensured that the written backups
> + are on disk. This is a good balance between speed and consistency,.
> + Note that the underlying storage device sitll needs to protect itself against
typo: still
> + powerloss to flush its internal ephemeral caches to the permanent storage layer.
> +
> + - `file` With this mode, a fsync is triggered on every chunk insertion, which
> + makes sure each and every chunk reaches the disk as soon as possible. While
> + this reaches the hightest level of consistency, for many storages (especially
typo: highest
> + slower ones) this comes at the cost of speed. For many users the `filesystem`
> + mode is better suited, but for very fast storages this mode can be ok.
> +
> + This can be set with:
> +
> +.. code-block:: console
> +
> + # proxmox-backup-manager datastore update <storename> --tuning 'sync-level=filesystem'
> +
> +If you want to set multiple tuning options simultaniously, you can seperate them
typo: simultaneously
> +with a comma, like this:
> +
> +.. code-block:: console
> +
> + # proxmox-backup-manager datastore update <storename> --tuning 'sync-level=filesystem,chunk-order=none'
next prev parent reply other threads:[~2022-10-10 7:54 UTC|newest]
Thread overview: 8+ messages / expand[flat|nested] mbox.gz Atom feed top
2022-10-07 11:54 [pbs-devel] [PATCH proxmox-backup v2 0/5] add 'sync-level' to datatore tuning options Dominik Csapak
2022-10-07 11:54 ` [pbs-devel] [PATCH proxmox-backup v2 1/5] docs: add information about chunk order option for datastores Dominik Csapak
2022-10-07 11:54 ` [pbs-devel] [PATCH proxmox-backup v2 2/5] pbs-datastore: chunk_store: use replace_file in insert_chunk Dominik Csapak
2022-10-07 11:54 ` [pbs-devel] [PATCH proxmox-backup v2 3/5] datastore: implement sync-level tuning for datastores Dominik Csapak
2022-10-07 11:54 ` [pbs-devel] [PATCH proxmox-backup v2 4/5] docs: add documentation about the 'sync-level' tuning Dominik Csapak
2022-10-10 7:54 ` Matthias Heiserer [this message]
2022-10-10 14:38 ` Daniel Tschlatscher
2022-10-07 11:54 ` [pbs-devel] [PATCH proxmox-backup v2 5/5] datastore: make 'filesystem' the default sync-level Dominik Csapak
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=293c5b4f-6f22-511a-a367-38411f677a73@proxmox.com \
--to=m.heiserer@proxmox.com \
--cc=d.csapak@proxmox.com \
--cc=pbs-devel@lists.proxmox.com \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox