[LEDE-DEV] [RFC 3/3] config: ext4: use 1K blocks by default to support online resize2fs

[Michael Heimpold]

Hi,

Am Montag, 17. Oktober 2016, 22:08:06 CEST schrieb Jo-Philipp Wich:
> Hi Michael,
> 
> > I can't see why adjusting the default partition size would have been
> > necessary
> > as genext2fs takes (or better: took) the following parameters:
> The filesystem is generated okay but due to the total size : blocksize ratio
> there are not enough backup block group descriptor entries left to support
> online-resizing the rootfs partition, see
> http://lists.infradead.org/pipermail/lede-dev/2016-September/002518.html
> for a report that describes the problem.

I understand the problem and solving this issue would be a great benefit.

> I am fine with keeping 4k blocks but in this case we should increase the
> default image size to at least the minimum value being able to support
> resizing. The report mentions that 512M already work which would allow
> resizing up to 512GB (1024 times larger).
> > Sorry, but I can only find the default value of 48 MB? Do I miss
> > something?
> 
> See
> https://git.lede-project.org/?p=source.git;a=blob;f=config/Config-images.in
> #l263
> > I don't like reverting to 1k because when you use the image on a real
> > device, e.g. eMMC or SD card, then usually the internal blocksize is 4k,
> > and internal erase block size is often even 4 MiB.
> > Thus using 1k blocksize is not optimal when using a writeable filesystem.
> 
> I understand. As mentioned above, 4K blocks are fine for me too, but in this
> case I suggest to bump the rootfs part size to 2GB which would support 2TB
> rootfs partitions.
> 

In general, I'm fine with larger default partition size. However, this results
in large images available for download at downloads.lede-project.org...

mhei