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From:   "Alan C. Assis" <acassis@gmail.com>
Date:   Mon, 17 Jul 2023 10:50:50 -0300
Message-ID: <CAG4Y6eTU=WsTaSowjkKT-snuvZwqWqnH3cdgGoCkToH02qEkgg@mail.gmail.com>
Subject: Re: File system robustness
To:     Kai Tomerius <kai@tomerius.de>
Cc:     linux-embedded@vger.kernel.org
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Hi Kai,

On 7/17/23, Kai Tomerius <kai@tomerius.de> wrote:
> Hi,
>
> let's suppose an embedded system with a read-only squashfs root file
> system, and a writable ext4 data partition with data=journal.
> Furthermore, the data partition shall be protected with dm-integrity.
>
> Normally, I'd umount the data partition while shutting down the
> system. There might be cases though where power is cut. In such a
> case, there'll be ext4 recoveries, which is ok.
>
> How robust would such a setup be? Are there chances that the ext4
> requires a fsck? What might happen if fsck is not run, ever? Is there
> a chance that the data partition can't be mounted at all? How often
> might that happen?
>

Please take a look at this document:

https://elinux.org/images/0/02/Filesystem_Considerations_for_Embedded_Devices.pdf

In general EXT4 is fine, but it has some limitation, more info here:
https://opensource.com/article/18/4/ext4-filesystem

I think Linux users suffer from the same problem we have with NuttX (a
Linux-like RTOS): which FS to use?

So for deep embedded systems running NuttX I follow this logic:

I need better performance and wear leveling, but I don't need to worry
about power loss: I choose SmartFS

I need good performance, wear leveling and some power loss protection: SPIFFS

I need good performance, wear leveling and good protection for
frequent power loss: LittleFS

In a NuttShell: There is no FS that 100% meets all user needs, select
the FS that meets your core needs and do lots of field testing to
confirm it works as expected.

BR,

Alan