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From: "Christoph Heiss" <c.heiss@proxmox.com>
To: "Daniel Kral" <d.kral@proxmox.com>
Cc: Proxmox VE development discussion <pve-devel@lists.proxmox.com>
Subject: Re: [pve-devel] [RFC PATCH 2/2] common: btrfs: lower minimum amount of disks for raid10 to 2
Date: Mon, 14 Apr 2025 13:57:52 +0200	[thread overview]
Message-ID: <D96CDTWXQK94.1BPVT80KWSDDW@proxmox.com> (raw)
In-Reply-To: <20250110170040.201474-2-d.kral@proxmox.com>

On Fri Jan 10, 2025 at 6:00 PM CET, Daniel Kral wrote:
> As the installer allows single-disk RAID0 configurations and BTRFS
> allows to create a filesystem with the RAID10 profile with only two
> disks since kernel version 5.15 [0], lower the minimum amount of disks
> the installer requires for a BTRFS RAID10 setup.
>
> The motiviation for this is to allow users to create a BTRFS RAID10
> configuration even though they do not have the necessary disks ready at
> setup time itself without needing to convert the profile afterwards.

Thinking about it, it does not really makes that much sense to allow
users to create degraded RAIDs - that just asks for all sorts of
troubles down the road in my book.

ZFS does not allow it either (or supports it AFAIK), for a good reason.
So IMHO we should not allow it with Btrfs as well.

*Especially* since Btrfs allows one to later on add more devices to a
filesystem and rebalance it to different profiles, e.g. from a RAID1 to
a RAID10 using

# btrfs balance start -mconvert=raid10 -dconvert=raid10 <mountpoint>

`-d` and `-m` of course depending on whether you'd want data block
and/or metadata chunks to be rebalanced.


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  parent reply	other threads:[~2025-04-14 11:57 UTC|newest]

Thread overview: 8+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2025-01-10 17:00 [pve-devel] [RFC PATCH 1/2] install: btrfs: fix raid level falling back to single mode Daniel Kral
2025-01-10 17:00 ` [pve-devel] [RFC PATCH 2/2] common: btrfs: lower minimum amount of disks for raid10 to 2 Daniel Kral
2025-01-13 12:24   ` Fabio Fantoni via pve-devel
     [not found]   ` <0999b2e1-8b8b-4baf-84d6-32251a675338@m2r.biz>
2025-01-15  9:00     ` Daniel Kral
2025-01-15 16:14       ` Fabio Fantoni via pve-devel
2025-04-14 11:57   ` Christoph Heiss [this message]
2025-01-13 12:15 ` [pve-devel] [RFC PATCH 1/2] install: btrfs: fix raid level falling back to single mode Fabio Fantoni via pve-devel
2025-04-14 12:20 ` Christoph Heiss

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