[LEDE-DEV] [RFC v2 3/3] config: ext4: increase x86 rootfs size to 2GB to support online resize2fs

Felix Fietkau nbd at nbd.name
Sat Oct 29 02:12:24 PDT 2016

On 2016-10-25 13:02, Jo-Philipp Wich wrote:
> The current default rootfs size of 256MB in conjunction with 4K blocks
> produces an ext4 filesystem which lacks the appropriate amount of backup GDT
> entries to support online-resizing.
> For x86 targets, increase the default rootfs size to 2048MB which allows
> online resizing the filesystem to up to 2TB which is the current theoretical
> maximum for LEDE, due to missing GPT support on the root block device.
> Note that the filesystem artefact will not occupy 2GB on the build system as
> the make_ext4fs utility uses sparse files to generate the filesystem images,
> so the actual disk usage is much lower. Furthermore the filesystem images
> are gzip compressed, shrinking them to only a few megabytes on the download
> server.
> Signed-off-by: Jo-Philipp Wich <jo at mein.io>
I think 2 GB is excessive. Due to the way that sysupgrade works, having
such a large rootfs partition is often not very useful anyway, since
everything except for config files gets lost.
It significantly increases build time and the amount of time it takes to
transfer an image to a flash medium.

In my opinion it's much more useful to keep the rootfs small and add a
data partition covering the rest of the medium, which then gets
preserved across upgrades.

- Felix

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